The geographic distribution and diversity of ethnic groups in Nepal reflect the migrations of groups displaced by or escaping adverse sociopolitical conditions in central, southern, and southeastern Asia. For instance, there is evidence that people from Southeast Asia moved into the Himalayan region in flight from the expanding Han dynasty during the first millennium B . C . It is also well documented that groups from north India moved into Nepal during various waves of the Muslim invasions during the fourteenth century. Further, the military and administrative consolidation of the Gorkha regime in the eighteenth century united the eighty or so ethnically varied principalities in the region and asserted an orthodox, Hindu sociopolitical and religious order. This led to the legislative designation of singular ethnic groups such as the Tamang, which often encompass diverse peoples. The formation of the nation-state of Nepal and its need for resources of grain and labor also forced the expanded settlement of the region and led to migrations of families to India to escape the demands of the state.