In the medieval period, the twofold frontier of mobile wealth, nomadic and maritime, largely developed under the aegis of Islam. This chapter analyses the establishment of Indo-Islamic conquest states by post-nomadic Turks, Mongols, Afghans, and others. Mass conversion to Islam only occurred in the Indus borderlands under the impact of widespread nomadic destruction over extended periods of time. In the post-nomadic states of the subcontinent there was no nomadic destruction but instead a fusion of frontier and settled society and little or no conversion to Islam. In the same centuries, the rise of Islam in the littoral regions and island archipelagos of the Indian Ocean took place in the context of the steadily expanding trade and increased dynamism of the medieval centuries – largely beyond the pale of settled Hindu society.