The earliest evidence of Islam in Mongolia is dated to 1254 when the Franciscan William of Rubruck visited the court of the great khan Mongka at Karakorum. He celebrated Easter at a Nestorian Christian church but also noted seven temples of the "idolators" (possibly Buddhist, Hindu and Taoist temples) and two mosques. Therefore, historians date the arrival of Islam to Mongolia to between 1222 and 1254.