at its height, Tang China was the largest and most powerful empire in the world. During the Sui and Tang dynasties, a professional civil-service bureaucracy rose to prominence. Tang power and influence was felt throughout Asia and even the Middle East. The blend of new and foreign ideas contributed to a rich mixture of tradition and cultural fruition. Many ideas from the West made their way into China along the Silk Roads during this period. Buddhism was the strongest foreign influence. When China began to suffer from foreign invasion toward the end of the Tang, Buddhism suffered imperial persecution. Taoism, however, flourished during this period and gained much imperial support. The Tang emperors, in fact, believed themselves to be the descendants of Laozi.