Tibetan Buddhism also includes a number of lay clergy and lay tantric specialists, such as Ngagpas (Skt. mantrī), Gomchens, Serkyims, and Chödpas (practitioners of Chöd). According to Samuel, in the more remote parts of the Himalayas, communities were often led by lay religious specialists. Thus, while the large monastic institutions were present in the regions of the Tibetan plateau which were more centralized politically, in other regions they were absent and instead smaller gompas and more lay oriented communities prevailed.