Islam had given rise to a brilliant new civilization that stretched from Spain to India. Hindu and Buddhist traditions flourished. Indian mathematicians invented a number system. China had a strong central government and made advances in technology, inventing paper, printing, and gunpowder. In West Africa, the Soninke people were building the great trading empire of Ghana. In the Americas the Mayas had cleared rainforests and built cities and dominated by towering temples. Byzantine empire was generally prosperous and united. The Seljuk Turks invaded the Byzantine Empire.