Although fighting in Pontiac's War began in 1763, rumors reached British officials as early as 1761 that discontented American Indians were planning an attack. Senecas of the Ohio Country (Mingos) circulated messages ("war belts" made of wampum) calling for the tribes to form a confederacy and drive away the British. The Mingos, led by Guyasuta and Tahaiadoris, were concerned about being surrounded by British forts. Similar war belts originated from Detroit and the Illinois Country. The Indians were not unified, and in June 1761, natives at Detroit informed the British commander of the Seneca plot. William Johnson held a large council with the tribes at Detroit in September 1761, which provided a tenuous peace, but war belts continued to circulate. Violence finally erupted after the Indians learned in early 1763 of the imminent French cession of the "pays d'en haut" to the British.