 Han China had economic contacts with Persia and the Roman empire, trading silk, minerals, and spices through the famous Silk Road.During the Tang dynasty, China had a multitude of religions that invigorated the many dynamic aspects of Tang cultural and intellectual life, a productive economy that generated substantial tax revenues to fund a competent, credible, and efficient political bureaucracy that administered a vast empire as well as possessing the world's most advanced science and technology at the time.By 1100, the Song dynasty hosted a population of almost 100 million people while large cities had over 1 million inhabitants, a sophisticated medieval economic system boasting the use of paper money (written business contracts, mercantile credits, checks, promissory notes, bills of exchange), and was a maritime naval power with extensive and flourishing trade contacts with Southeast Asia.