after the arrival of indo-aryans, the kingdoms around bengal were first described in the "atharvaveda" about 1000 bc. from the 6th century bc, magadha expanded to include most of the bihar and bengal regions. it was one of the four main kingdoms of india at the time of buddha. magadha extended over nearly all of south asia, including parts of persia and afghanistan, reaching its greatest extent under the buddhist emperor ashoka the great in the 3rd century bc. one of the earliest foreign references to bengal is the mention of a land ruled by the king xandrammes named gangaridai by the greeks around 100 bc. the word is speculated to have come from "gangahrd" (land with the ganges in its heart) in reference to an area in bengal. later from the 3rd to the 6th centuries ad, the kingdom of magadha served as the seat of the gupta empire.