The expansion of wet-rice agriculture by the middle of the first millennium BCE and, apparently more importantly, certain requirements of trade such as the control of local commodities, suggest new social and political possibilities, which are seized by some communities in Indonesia.

For reasons not well understood, most—and all of those that endured—are located in the western archipelago.

Already acquainted with a wider world, these Indonesians are open to, and indeed actively seek out, new ideas of political legitimation, social control, and religious and artistic expression.

Their principal sources lie not in China, with which ancient Indonesians are certainly acquainted, but in South Asia, in present-day India and Sri Lanka, whose outlooks appear to have more nearly reflected their own.

This process of adoption and adaptation, which scholars have somewhat misleadingly referred to as a rather singular "Hinduization" or "Indianization," is perhaps better understood as one of localization or "Indonesianization" of multiple South Asian traditions.

It involves much local selection and accommodation (there are no Indian colonizations), and it undoubtedly began many centuries before its first fruits are clearly visible through the archaeological record.

Early Indonesia does not become a mini-India.

Artistic and religious borrowings are never exact replications, and many key Indian concepts, such as those of caste and the subordinate social position of women, are not accepted.

Selected ideas fill particular needs or appeal to particular sensibilities, yet at the same time they are anything but superficial; the remnants of their further elaboration are still very much in evidence today.

Some Indonesian peoples probably began writing on perishable materials at an earlier date, but the first stone inscriptions (in Sanskrit, using an early Pallava script from southern India) date from the end of the fourth century CE (in the eastern Kalimantan locale of Kutai) and from the early or mid-fifth century CE (in the western Java polity known as Taruma).

These inscriptions offer a glimpse of leaders newly envisioning themselves not as mere chiefs (datu) but as kings or overlords (raja, maharaja), taking Indian names and employing first Brahmanical Hindu, then Buddhist, concepts and rituals to invent new traditions justifying their rule over newly conceived social and political hierarchies.

In addition, Chinese records from about the same time provide scattered, although not always reliable, information about a number of other "kingdoms" on Sumatra, Java, southwestern Kalimantan, and southern Sulawesi, which, in the expanding trade opportunities of the early fifth century, have begun to compete with each other for advantage, but we know little else about them.

Historians have commonly understood these very limited data to indicate the beginnings of the formation of "states," and later "empires" in the archipelago, but use of such terms is problematic.

We understand that small and loosely organized communities consolidated and expanded their reach, some a great deal more successfully than others, but even in the best-known cases we do not have sufficient specific knowledge of how these entities actually worked to compare them confidently with, for example, the states and empires of the Mediterranean region during the same period or earlier.

More generalized terms, such as "polities" or "hegemonies," are suggestive of social and political models that are more applicable.

Sikhottabong is a mandala whose capital is located on the left bank of the Mekong at the mouth of the Xe Bangfai and then moves westward as a result of the expansion of Champa, an Indianized state on the coast of Vietnam founded in CE 192.

Cham, descendants of Champa, are present at Champasak (Bassac) in the fifth century.

The Mon kingdom of Candapuri, the earliest name of present-day Vientiane (Viangchan), is another mandala.

The social structure of Sikhottabong and Candapuri appears to have been strongly hierarchical, with an aristocracy, a commoner class, and a slave class.

The fact that some kings come from the commoner class appears to indicate the presence of some sort of consensus in effecting royal succession.

At its peak, another important regional power, Funan, has its mandala incorporate parts of central Laos.

The smaller, but also important, Mon kingdom of Dvaravati (through which Theravada Buddhism will reach Laos in the seventh and eighth centuries) is centered in the lower Menam Valley beginning in the fifth century.

The original inhabitants of Laos were Austroasiatic peoples, who lived by hunting and gathering before the advent of agriculture.

Skilled at river navigation using canoes, these Laotian traders used routes through the mountains, especially rivers, from earliest times.

The most important river route is the Mekong because its many tributaries allow traders to penetrate deep into the hinterland, where they buy products such as cardamom, gum benzoin, sticklac, and many foods.

A number of princely fiefdoms based on wet rice cultivation and associated with the pottery and bronze culture of Ban Chiang have developed in the middle Mekong Valley from the first century CE.

These fiefdoms exercise power over their neighbors, in circumstances of generally sparse populations, through expanding and contracting spheres of influence best described by the term mandala.

Commerce, marriage contracts, and warfare serve to expand the mandala.

Thus, a plurality of power centers occupy the middle Mekong Valley in early times.

The Funan state exercises control over the lower Mekong River area and the lands around the Tonle Sap by the fifth century CE.

It also commands tribute from smaller states in the area now comprising northern Cambodia, southern Laos, southern Thailand, and the northern portion of the Malay Peninsula.

Indianization is fostered by increasing contact with the subcontinent through the travels of merchants, diplomats, and learned Brahmans (Hindus of the highest caste traditionally assigned to the priesthood).

Indian immigrants, believed to have arrived in the fourth and the fifth centuries, accelerate the process.

By the fifth century, the elite culture is thoroughly Indianized.

Court ceremony and the structure of political institutions are based on Indian models.

The Sanskrit language is widely used; the laws of Manu, the Indian legal code, are adopted; and an alphabet based on Indian writing systems is introduced.

Maritime East Asia (388–531 CE): Consolidation of States, Cultural Flourishing, and Technological Advancements

Between 388 CE and 531 CE, Maritime East Asia—comprising lower Primorsky Krai, the Korean Peninsula, the Japanese Archipelago below northern Hokkaido, Taiwan, and southern, central, and northeastern China—witnesses the consolidation of major kingdoms, cultural flourishing, and important technological innovations.

Consolidation and Expansion in Korea: Silla, Baekje, and Goguryeo

Silla, evolving from the walled town of Saro, is consolidated under King Naemul (r. 356–402), establishing a hereditary monarchy east of the Naktong River. By the early sixth century, Silla significantly advances agricultural productivity through oxen plowing and extensive irrigation, enabling greater political stability and cultural development. In 520 CE, an administrative code is adopted, followed by Buddhism becoming the state religion around 535 CE. The bone-rank system emerges, codifying an aristocratic social hierarchy where status and lineage are paramount.

Baekje, after successfully repelling an attack from the Chinese-held region of Lelang in 246 CE, maintains its influential aristocratic state structure, integrating Buddhism officially as the state religion in 384 CE under royal patronage.

Goguryeo, a formidable northern power, continues expansion into Lelang and the broader Korean Peninsula. Its geographic position, marked by harsh climates and mountainous terrain, strengthens its distinct cultural identity, later emphasized in North Korean historiography.

The Gaya Confederacy, consisting of states along the south-central peninsula, maintains close ties with Japan but is eventually absorbed by Silla, despite Japanese military intervention on Gaya’s behalf in 399 CE.

The Yamato Polity and Aristocratic Transformation in Japan

In Japan, the Yamato polity emerges prominently in the mid-Kofun period, defined by influential great clans. Clan patriarchs perform sacred rites to ensure welfare, with a hereditary aristocracy beginning to replace tribal leadership structures. Aristocratic status increasingly determines political influence, shifting power dynamics away from purely clan-based hierarchies.

Political Fragmentation and Cultural Flourishing in China

China experiences continued political fragmentation during the Sixteen Kingdoms (304–439 CE) and the subsequent Southern and Northern Dynasties period (420–589 CE). Despite persistent warfare and instability, this era is culturally vibrant, characterized by advancements in art, science, and religion.

Significant technological innovations include the widespread adoption of the stirrup by 477 CE, enhancing military effectiveness. Additionally, Chinese architecture evolves distinctly, with the development of the pagoda, derived from Buddhist stupa traditions, becoming prominent for housing Buddhist scriptures.

Buddhism and Cultural Exchange

Buddhism spreads widely across China, notably through the influential translations by Kumarajiva, facilitating its integration into Chinese society. By the late fifth century, the distinct Ch’an (Zen) Buddhism emerges prominently, attributed to the teachings of Bodhidharma, emphasizing contemplative meditation as a pathway to enlightenment.

Artistic and Architectural Achievements

Monumental stone sculpture flourishes, exemplified by the Yungang Grottoes near Pingcheng (modern-day Datong). Under imperial patronage of the Northern Wei Dynasty, the caves house immense rock-cut Buddha sculptures, showcasing Central Asian artistic influences. This monumental art form persists through imperial and private support until political upheavals halt further construction by 525 CE.

Legacy of the Age: State Consolidation and Cultural Innovation

Thus, the age from 388 to 531 CE is marked by significant state consolidation, particularly in Korea and Japan, combined with cultural and technological innovations across East Asia. These developments lay foundational structures influencing political, social, and cultural trajectories well into subsequent centuries.

Silla evolves from a walled town called Saro.

Silla chroniclers are said to have traced its origins to 57 BCE, but contemporary historians have regarded King Naemul (r. CE 356-402) as the ruler who first consolidates a large confederated kingdom and establishes a hereditary monarchy.

His domain is east of the Naktong River in today's North Kyongsang Province.

A small number of states located along the south-central tip of the peninsula facing the Korea Strait do not join either Silla or Baekje but instead form the Gaya Confederacy, which maintains close ties with states in Japan.

Silla eventually absorbs the neighboring Gaya states in spite of an attack by Wa forces from Japan on behalf of Gaya in 399, which Silla repels with help from Goguryeo.

Centralized government probably emerges in Silla in the second half of the fifth century, as the capital became both an administrative and a marketing center.

In the early sixth century, Silla's leaders introduce plowing by oxen and build extensive irrigation facilities.

Increased agricultural output presumably ensues, allowing further political and cultural development, including an administrative code in 520, a hereditary caste structure known as the bone-rank system to regulate membership of the elite, and the adoption of Buddhism as the state religion around 535.

Status in Silla society is so much influenced by birth and lineage that the bone-rank system leads each family and clan to maintain extensive genealogical records with meticulous care.

Because only male offspring prolong the family and clan lines and are the only names registered in the genealogical tables, the birth of a son is greeted with great felicitation.

The elite, of course, is most conscious of family pedigree.

The Yamato polity, which emerges in the mid-Kofun period, is distinguished by powerful great clans or extended families, each with its dependents.

Each clan is headed by a patriarch who perform sacred rites to the clan's kami to ensure the long-term welfare of the clan.

Clan members are the aristocracy, and the kingly line that controls the Yamato court is at its pinnacle.

The invention of the stirrup, which appears to be in widespread use across China by 477 CE, gives great support for the rider, and will be essential in later warfare.