His brother Byang chub 'Od (984–1078), a Buddhist monk, took power as secular ruler. He was responsible for inviting Atiśa to Tibet in 1040 and thus ushering in the so-called Chidar (Phyi-dar) phase of Buddhism in Tibet. Byang chub 'Od's son rTse lde was murdered by his nephew in 1088. This event marked the break-up of the Guge-Purang kingdom, since one of his brothers was established as separate king of Purang. The usurping nephew dBang lde continued the royal dynasty in Guge. A new Kara-Khanid invasion of Guge took place before 1137 and cost the life of the ruler, bKra shis rtse. Later in the same century the kingdom was temporarily divided. In 1240 the Mongol khagan, at least nominally, gave authority over the Ngari area to the Drigung Monastery in Ü-Tsang. Grags pa lde was an important ruler who united the Guge area around 1265 and subjugated the related Ya rtse (Khasa) kingdom. After his death in 1277 Guge was dominated by the Sakya monastic regime. After 1363, with the decline of the Mongol-led Yuan dynasty and their Sakya protégés, Guge was again strengthened and took over Purang in 1378. Purang was henceforth contested between Guge and Mustang, but was finally integrated into the former. Guge also briefly ruled over Ladakh in the late 14th century. From 1499 the Guge king had to acknowledge the Rinpungpa rulers of Tsang. The 15th and 16th centuries were marked by a considerable Buddhist building activity by the kings, who frequently showed their devotion to the Gelug leaders later known as the Dalai Lamas. Ladakhi invasions The first Westerners to reach Guge were António de Andrade, a Jesuit missionary, and his companion brother Manuel Marques, in 1624. De Andrade reported seeing irrigation canals and rich crops in what is now a dry and desolate land. Perhaps as evidence of the kingdom's openness, de Andrade's party was allowed to construct a chapel in Tsaparang and instruct the people about Christianity. A letter by De Andrade relates that some military commanders revolted and called the Ladakhis to overthrow the ruler. There had been friction between Guge and Ladakh for many years, and the invitation was heeded in 1630. The Ladakhi forces laid siege to the almost impenetrable Tsaparang. The King's brother, who was chief lama and thus a staunch Buddhist, advised the pro-Christian ruler to surrender against keeping the state as tributary ruler. This treacherous