The rapid proliferation of data documenting species’ geographic distributions, their underlying phylogenetic relationships, and their ecological traits has begun to lift the veil obscuring the fundamental biological mechanisms organizing species geographically. In the 3 chapters of this thesis, I combine these types of data with local field surveys to assess the composition of local communities that span the tropical-temperate boundary and assess their associations to the surrounding region. I develop a framework for understanding species’ geographic associations using a wide diversity of data-types by leveraging a novel machine learning method that has so far not been developed in the context of studying biogeography. Most of this research is focused on birds of the Himalayas, the second most diverse location on earth for avian life. The final chapter focuses on composition of bird and mammal assemblages of the Indo-Pacific, in particular evaluating the composition of these groups in relation to the famous biogeographic partition designated by Wallace.