In states that are diverse, issues of national identity formation and who belongs and how they belong can, and often do, change over time. This article analyses how education was used as a tool to artificially create antagonistic national identities based on religious and ethnic definitions of who was Indian or Pakistani. It focuses in particular on how in India the BJP led government (1998-2004) and in Pakistan the government under General Zia-ul-Haq (1977-1988) rewrote the curricula and changed textbook content in order to create the 'other' in order to suit their ideology and the politics of the day. Drawing on the original textbooks, extensive fieldwork interviews in both countries and a study of recent literature the paper argues that fundamentalization in general and the fundamentalization of textbooks in particular are state controlled mechanisms through which to control society. They can also have serious international consequences, as two antagonistic national identities oppose each other's definition of history and self. (Contains 14 notes.)