The Kingdom of Pagan (also commonly known as the Pagan Dynasty and the Pagan Empire) is the first kingdom to unify the regions that would later constitute modern-day Burma (Myanmar).

Pagan's 250-year rule over the Irrawaddy valley and its periphery lay the foundation for the ascent of Burmese language and culture, the spread of Burman ethnicity in Upper Burma, and the growth of Theravada Buddhism in Burma and in mainland Southeast Asia.

The kingdom grows out of a small 9th-century settlement at Pagan (Bagan) by the Mranma (Burmans), who had recently entered the Irrawaddy valley from the Kingdom of Nanzhao.

Over the next two hundred years, the small principality gradually grows to absorb its surrounding regions until the 1050s and 1060s when King Anawrahta founds the Pagan Empire, for the first time unifying under one polity the Irrawaddy valley and its periphery.

By the late 12th century Anawrahta's successors have extended their influence farther to the south into the upper Malay peninsula, to the east at least to the Salween river, in the farther north to below the current China border, and to the west, in northern Arakan and the Chin Hills.

In the 12th and 13th centuries, Pagan, alongside the Khmer Empire, is one of two main empires in mainland Southeast Asia.

The Burmese language and culture gradually become dominant in the upper Irrawaddy valley, eclipsing the Pyu, Mon and Pali norms by the late 12th century.

Theravada Buddhism slowly begins to spread to the village level although Tantric, Mahayana, Brahmanic, and animist practices remain heavily entrenched at all social strata.

Pagan's rulers build over 10,000 Buddhist temples in the Pagan capital zone of which over 2000 remain.

The wealthy donate tax-free land to religious authorities.

The kingdom goes into decline in the mid-13th century as the continuous growth of tax-free religious wealth by the 1280s has severely affected the crown's ability to retain the loyalty of courtiers and military servicemen.

This ushes in a vicious circle of internal disorders and external challenges by the Arakanese, Mons, Mongols and Shans.

Repeated Mongol invasions (1277–1301) topple the four-century-old kingdom in 1287.

The collapse is followed by 250 years of political fragmentation that lasts well into the 16th century.