Polygamy was common in 7th-century Arabia, as it has been in many other cultures, especially for a political leader; for instance, the patriarchs in the Hebrew Bible are shown as having multiple wives, and the kings of Israel are described as having harems numbering in some cases into the hundreds. According to Muslim historians, the Prophet Muhammad’s marriages were contracted to assist needy widows and divorcees and to solidify the community of Muslims by forging alliances among the tribes in and around Medina. In light of the time and place, there was nothing unique or unusual about Muhammad marrying several women.
Rather, it was quiet the norm. But the marriages of the Prophet Muhammad were unique in the sense that he married widows, divorcees and foreign women from distant tribes. All this first and fore mostly, to protect the weak and vulnerable in society by providing security and protection to these women.