The palynological assemblages comprising angiospermous pollen, pteridophytic spores, fungal remains, gymnospermous pollen, dinoflagellate cysts, acritarchs and reworked Permian spores and pollen have been reported from Siwalik sediments exposed in Kameng, Subansiri and Siang districts, Arunachal Pradesh. Palynological comparison with extant plants has been attempted to determine the palaeo-vegetation, Palaeoclimate and environment of deposition. Geological history and palaeogeography of Neogene sediments of Arunachal Himalaya have been discussed.

Palynotaxa, viz., Ctenolophonidites, Lakiapollis, Tricolporopollis, Pellicieroipollis and Incrotonipollis, have been recovered from the sediments exposed near Rengging along the Siang River, on Yinkiyong-Gobuik road, and near Dalbing in the Yamne Valley in Siang District, Arunachal Pradesh. Recovery of these palynotaxa provides additional evidence for the occurrence of Early Tertiary sediments in Arunachal foot-hills and Lesser Himalaya.