The Treaty of Bassein (Now called Vasai) was a pact signed on December 31, 1802 between the British East India Company and Baji Rao II, the Maratha peshwa of Pune (Poona) in India after the Battle of Poona. The treaty was a decisive step in the dissolution of the Maratha Confederacy, which led to the East India Company’s usurpation of the peshwa’s territories in western India in 1818.