Asian portion of the empire (Bactria) seceded as the Greco-Bactrian Kingdom, which had extensive contacts with India and China until its end in 125 BC. The Indo-Greek Kingdom, mostly based in the Punjab region but controlling a fair part of Afghanistan, pioneered the development of Greco-Buddhism. The Kushan Kingdom thrived across a wide swath of the region from the 2nd century BC to the 4th century AD, and continued Hellenistic and Buddhist traditions. These states prospered from their position on the Silk Road linking China and Europe. Likewise, in eastern Central Asia, the Chinese Han dynasty expanded into the region at the height of its imperial power. From roughly 115 to 60 BC, Han forces fought the Xiongnu over control of the oasis city-states in the Tarim Basin. The Han was eventually victorious and established the Protectorate of the Western Regions in 60 BC, which dealt with the region's defence and foreign affairs. Chinese rule in Tarim Basin was replaced successively with Kushans and Hephthalites. Later, external powers such as the Sassanid Empire would come to dominate this trade. One of those powers, the Parthian Empire, was of Central Asian origin, but adopted Persian-Greek cultural traditions. This is an early example of a recurring theme of Central Asian history: occasionally nomads of Central Asian origin would conquer the kingdoms and empires surrounding the region, but quickly merge into the culture of the conquered peoples. At this time Central Asia was a heterogeneous region with a mixture of cultures and religions. Buddhism remained the largest religion, but was concentrated in the east. Around Persia, Zoroastrianism became important. Nestorian Christianity entered the area, but was never more than a minority faith. More successful was Manichaeism, which became the third largest faith. Turkic expansion began in the 6th century; the Turkic speaking Uyghurs were one of many distinct cultural groups brought together by the trade of the Silk Route at Turfan, which was then ruled by China's Tang dynasty. The Uyghurs, primarily pastoral nomads, observed a number of religions including Manichaeism, Buddhism, and Nestorian Christianity. Many of the artefacts from this period were found in the 19th century in this remote desert region. Medieval Sui and early Tang dynasty It was during the Sui and Tang dynasties that China expanded into eastern Central Asia. Chinese foreign policy to the north and west now had to deal with Turkic nomads, who were becoming the