As the arab empire declined why did islam continue to spread?

Muslim conquests in the death following Muhammad's death led to the creation of the caliphates, occupying a vast geographical area; conversion to Islam was boosted by missionary activities, particularly those of Imams, who intermingled with local populations to propagate the religious teachings.[1] These early caliphates, coupled with Muslim economics and trading and the later expansion of the Ottoman Empire, resulted in Islam's spread outwards from Mecca towards both the Atlantic and Pacific Oceans and the creation of the Muslim world. Trading played an important role in the spread of Islam in several parts of the world, notably southeast Asia.[2][3]

Muslim dynasties were soon established and subsequent empires such as those of the Abbasids, Fatimids, Almoravids, Seljukids, Ajuran, Adal and Warsangali in Somalia, Mughals in India and Safavids in Persia and Ottomans in Anatolia were among the largest and most powerful in the world. The people of the Islamic world created numerous sophisticated centers of culture and science with far-reaching mercantile networks, travelers, scientists, hunters, mathematicians, doctors and philosophers, all contributing to the Golden Age of Islam. Islamic expansion in South and East Asia fostered cosmopolitan and eclectic Muslim cultures in the Indian subcontinent, Malaysia, Indonesia and China.[4]

As of 2015, there were 2 billion Muslims,[5][6] with one out of four people in the world being Muslim,[7] making Islam the second-largest religion in the world.[8] Out of children born from 2010 to 2015, 31% were Muslim. Babies born to Muslims are expected to outnumber those to Christians by 2035.[9]

john maynard keynes developed new economic theories in response to the : b) great depression of the 1930s. his theories are so important that they are known as "keynesianism". in his works he supports the idea of a government with deeper involvement and intervention to end the great depression.