Upto Four wives are allowed in Islam. This has a historical reason as during the early period of the ascendance of Islam, when too many males died in the battles, they left behind widows and orphans. At this situation would have lead to destitution and prostitution, Muslim men of the time were allowed to marry 2, 3 or 4 women with the condition that they would support them fully and maintain equality between wives. This Quranic injunction is not a license to indulge in wanton pursuit of the pleasures of the fleah but rather a step towards bringing about social justice and save the hapless women from penury and life of disgrace. You would agree that living as second or third wife is better than indulging in adultery, prostitution or living as a Devdasi. It is very stnrage that the modern educated elite scoff at polygany but have no qualms at indulging in pre-marital and extra-marital sexual affairs. If any Muslim kings or emperors trangressed this limit, that is their problem. In any case, emperors are not the representatives of their faiths. It would be naive to presume otherwise. This names of kings provided in the article also illustrates that they belonged to different regions, faiths and eras. Why give the whole issue an anti-muslim twiest then?