The Chutia kingdom (also Sadiya) (Pron: /ˈsʊðiːjɑː/ or Sutia) was a late medieval state that developed around Sadiya in present Assam and adjoining areas in Arunachal Pradesh. It extended over almost the entire region of present districts of Lakhimpur, Dhemaji, Tinsukia, and some parts of Dibrugarh in Assam, as well as the plains and foothills of Arunachal Pradesh. The kingdom fell around the year 1523-24 to the Ahom Kingdom after a series of conflicts and the capital area ruled by the Chutia rulers became the administrative domain of the office of Sadia Khowa Gohain of the Ahom kingdom.

The Chutia kingdom, believed to be founded in the early 13th century around Sadiya and contiguous areas, came into prominence in the second half of the 14th century, and was one among several rudimentary states (Ahom, Dimasa, Koch, Jaintia etc.) that emerged from tribal political formations in the region after the fall of Kamarupa kingdom, between the 13th and the 16th century. Among these, the Chutia state was the most advanced, with its rural industries, trade, surplus economy and advanced Sanskritisation. It is not exactly known as to the system of agriculture adopted by the Chutias, but it is believed that they were settled cultivators. After the Ahoms annexed the kingdom in 1523-24, the Chutia state & its population was absorbed into the Ahom kingdom through Ahomisation — the nobility and the professional classes were given important positions in the Ahom officialdom and the land was resettled for wet rice cultivation.

Though there is no doubt on the Chutia polity, the origins of this kingdom are obscure. It is generally held that the Chutias, a grouping of different Bodo-Kachari cognate groups, established a state in the plains around Sadiya before the advent of the Ahoms in 1228. Though Buranjis, the Ahom chronicles, indicate the presence of a Chutia state the evidence is scarce that it was of any significance before the second half of the 14th century.

The earliest Chutia king in the epigraphic records is Nandin or Nandisvara, from the latter half of the 14th century, mentioned in a grant by his son Satyanarayana who nevertheless draws his royal lineage from Asuras in his mother's side who were "enemies of the gods". The mention of Satyanarayana as having the shape of his maternal uncle (which is also an indirect reference to the same Asura/Daitya lineage) may also constitute evidence of matrilineality of the Chutia ruling family, or that their system was not exclusively patrilineal. On the other hand, a later king Durlabhnarayana mentions that his grandfather Ratnanarayana (identified with Satyanarayana) was the king of Kamatapura which might indicate that the eastern region of Sadhaya was politically connected to the western region of Kamata.

In these early inscriptions, the kings are said to be seated in Sadhyapuri, identified with the present-day Sadiya; which is why the kingdom is also called Sadiya. The Buranjis written in the Ahom language called the kingdom Tiora (literal meaning: Burha Tai/Elder Tai) whereas those written in the Assamese language called it Chutia.

Brahmanical influence in the form of Vaishnavism reached the Chutia polity in the eastern extremity of present-day Assam during the late fourteenth century. Vaishnava Brahmins created lineages for the rulers with references to Krishna legends but placed them lower in the Brahminical social hierarchy because of their autochthonous origins. Though asura lineage of the Chutia rulers have similarities with the Narakasura lineage created for the three Kamarupa dynasties, the precise historical connection is not clear. Although a majority of the Brahmin donees of the royal grants were Vaishnavas, the rulers patronized the non-brahmanised Dikkaravasini (also Tamresvari or Kechai-khati), which was either a powerful tribal deity, or a form of the Buddhist deity Tara adopted for tribal worship. This deity, noticed in the 10th century Kalika Purana well before the establishment of the Chutia kingdom, continued to be presided by a Deori priesthood well into the Ahom rule and outside Brahminical influence.

Unfortunately, there are many manuscript accounts of the origin and lineage that do not agree with each other or with the epigraphic records and therefore have no historical moorings. One such source is Chutiyar Rajar Vamsavali, first published in Orunodoi in 1850 and reprinted in Deodhai Asam Buranji. Historians consider this document to have been composed in the early 19th century—to legitimize the Matak rajya around 1805—or after the end of Ahom rule in 1826. This document relates the legend of Birpal. Yet another Assamese document, retrieved by Ney Elias from Burmese sources, relates an alternative legend of Asambhinna. These different legends suggest that the genealogical claims of the Chutias have changed over time and that these are efforts to construct (and reconstruct) the past.

Only a few recently compiled Buranjis provide the history of the Chutia kingdom; though some sections of these compilations are old, the sections that contain the list of Chutiya rulers cannot be traced to earlier than 19th century and scholars have shown great disdain for these accounts and legends.