China reopened the Silk Road, allowing trade between China and the regions to its west to flourish. Tang armies repeatedly intervened in the western regions to preserve this state of peace and prosperity. The equal-field system did not allow large land transactions and thus during the early Tang estates remained small. The Tang government managed the economy through the bureaucratic regulation of markets, limiting the times where they could exchange goods, setting standards for product quality, and regulating prices of produce. During the Tang, the taxation system was based on the equal-field system, which equalised wealth among the farmers. The tax burden of peasants was based on population per household, rather than the value of property. The standard tax amounted to 2 tan (about 100 litres) of grain, as well as 2 Zhang (around 3 1/3 meters) and 5 Chi (about 1/3 of a meter) of cloth. The peasant was eligible for 20 days' conscripted labour; if he defaulted he was obliged to pay 3 Chi of cloth per day missed. Assuming each farmer had 30 mou of land which produced 1 tan of grain a year, the tax rate amounted to 25% of the farmer's income. Commercial taxes were lighter, at 3.3% of income. The Tang government operated a huge handicraft industry, separate from the private handicraft industry that served the majority of the population. The public handicraft industry provided the Tang government, army and nobility with various products. The government's handicraft industries retarded the growth of the private sector which did not develop rapidly until after the Anshi Rebellion, when the Tang government's interference in the economy (and the size of its government handicraft industries) drastically decreased. Despite this, a large number of households worked in private industry; scholars have estimated that 10% of Tang China's population lived in cities. The height of Tang prosperity came during the Kaiyuan Era of Emperor Xuanzong of Tang, who expanded Tang influence westward to the Aral Sea. Emperor Xuan was a capable administrator, and his Kaiyuan Era is often compared with the earlier Zhenkuan era in efficiency of administration. After this era, the Tang dynasty went into decline. After the An Shi Rebellion Emperor Xuanzong's reign ended with the Arab victory at Talas and the An Shi Rebellion, the first war inside China in over 120 years, led by a Sogdian general named An Lushan who used a large number of