were led by Chancellor Sima Guang and Empress Dowager Gao, regent of the young Emperor Zhezong of Song. Heated political debate and sectarian intrigue followed, while political enemies were often dismissed from the capital to govern frontier regions in the deep south where malaria was known to be very fatal to northern Chinese people (see History of the Song dynasty). This period also represents a high point in classical Chinese science and technology, with figures such as Su Song and Shen Kuo, as well as the age where the matured form of the Chinese pagoda was accomplished in Chinese architecture. In Japan, the Fujiwara clan dominated central politics by acting as imperial regents, controlling the actions of the Emperor of Japan, who acted merely as a 'puppet monarch' during the Heian period. In Korea, the rulers of the Goryeo Kingdom were able to concentrate more central authority into their own hands than in that of the nobles, and were able to fend off two Khitan invasions with their armies. In the Middle East, the Fatimid Empire of Egypt reached its zenith only to face steep decline, much like the Byzantine Empire in the first half of the century. The Seljuks came to prominence while the Abbasid caliphs held traditional titles without real, tangible authority in state affairs. In India, the Chola dynasty reached its height of naval power under leaders such as Rajaraja Chola I and Rajendra Chola I, dominating southern India (Tamil Nadu), Sri Lanka, and regions of Southeast Asia. The Ghaznavid Empire would invade northwest India, an event that would pave the way to a series of later Muslim expansions into India. In Southeast Asia, the Pagan Kingdom reached its height of political and military power. The Khmer Empire would dominate in Mainland Southeast Asia while Srivijaya would dominate Maritime Southeast Asia. Further east, the Kingdom of Butuan, centered on the northern portion of Mindanao island flourished as the dominant trading polity in the archipelago. In Vietnam, the Lý dynasty began, which would reach its golden era during the 11th century. In Nigeria, formation of city states, kingdoms and empires, including Hausa kingdoms and Borno dynasty in the north, and the Oyo Empire and Kingdom of Benin in the south. Events 1001–1009 1001: Mahmud of Ghazni, Muslim leader of Ghazni, begins a series of raids into Northern India; he finishes in 1027 with the destruction of Somnath. c.