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.