The Pagan Empire collapsed in 1287 due to repeated Mongol invasions (1277–1301). Recent research shows that Mongol armies may not have reached Bagan itself, and that even if they did, the damage they inflicted was probably minimal. However, the damage had already been done. The city, once home to some 50,000 to 200,000 people, had been reduced to a small town, never to regain its preeminence. The city formally ceased to be the capital of Burma in December 1297 when the Myinsaing Kingdom became the new power in Upper Burma.