An assemblage of fossil leaves is described from the late Oligocene (Chattian 28.1–23 Ma) sediments of Assam, which was located in a low palaeolatitude (∼10$–15°N) during the period of sedimentation. It includes four new fossil leaves resembling Firmiana and Pterygota of the Malvaceae s.l. and Paranephelium and Sapindus of the Sapindaceae. The present study suggests that the floral migration between India and southeast Asia had occurred after the late Oligocene. Our study is in congruence with the earlier published data suggesting a floral migration had occurred after the complete suturing of two landmasses by the Neogene.