The National Interest has published an article informing us about 5 most powerful empires of the History, the Ummayad Arab-Islamic empire [that is, known as Islamic Caliphate] is listed as one of the most powerful empires of the history.
The Arab-Islamic Empire, also known as the Caliphate, was a political entity that encompassed most of Arabia*. It is more reasonable to call this the Arab Empire rather than the Muslim Empire because while Islam originated and spread because of this empire, there were many subsequent empires that were legally Muslim or ruled by Muslims but were not Arab such as Mughal, Ottoman, Timurid, Ghaznawid, etc.
*the first political entity of Arab empire is Rashidun Caliphate under Rightly-Guided Caliphs and then turned into Ummayad Arab Empire that ruled until 750 C.E.
Prophet Muhammad (peace and blessings be upon him) was succeeded by the four Rightly-Guided Caliphs (“successors”) who were selected by consensus and acclimation (though not undisputed) until 661 C.E. The hereditary Umayyad Caliphate then ruled until 750 C.E., followed by the Abbasid Caliphate, though conquests had ended by this point. The Arab Empire effectively ended around 900 C.E., although the Abbasids maintained their religious role as figurehead Caliphs in Baghdad until the destruction of that city by the Mongols in 1258 C.E. After 900 C.E., the empire began to crumble politically with the rise of rival dynasties, many of them were Turkic and Persian in origin, as well as rival Caliphates in Spain and Egypt [The Abassid Arab empire never ruled the entire Islamic world, they had challenges for their legitimacy, the two empires Fatimid in Egypt and Ummayad in Spain challenged the authority of Abbasid over the Muslim world].
Nonetheless, in its own time, the Arab Empire was extraordinary, both because of its military successes and because of its legacy. It is amazing that a loosely organized, tribal people on the fringes of world civilization defeated the Byzantine Empire and overthrew the Sassanid Persian Empire, both of whose populations and resource bases dwarfed the Arabian Desert. The Arab conquests are a good example of how the faith can sometimes make up for technological and organizational deficiencies, and Arab generals from this period deserve to be ranked among the world’s greatest military geniuses, especially the second Caliph Omar, who conquered the region from Egypt to Persia in ten years. In a hundred years, the Arab Empire grew to be several times larger than the Roman Empire at its height.
Because of its location, the Arab Empire, like the Persian Empire before it, connected the other centers of world civilization in Africa, Europe, Central Asia, India, and China. As a result, goods and knowledge from all these regions were able to mix for the first time, giving rise to new concepts like algebra.
In conclusion, the Arab-Islamic empire is one of the most powerful empires of the history, it’s rich legacy from the Islam’s golden age has shaped the modern civilization*. The ultimate legacy of the Arab Empire, of course, is the religion of Islam, followed by more than a billion people today.
*In a speech to an enormous audience in 1972 Dr. Kris Traglor, an American professor of history at the Technical University of Texas, stated that the source of inspiration and development for the European Renaissance was Islam; that Muslims, coming to Spain and Sicily, had laid the foundations for modern techniques and developments and had taught that scientific progress would be possible only through improvement in chemistry, medicine, astronomy, navigation, geography, cartography and mathematics; and that these branches of knowledge had been brought to Europe from North Africa and Spain by Muslims. (Documents of the Right Word, pg 459 – Hakikat Bookstore, Istanbul)
NOTE: The quotation from the National Interest is modified here for my own commentary on the topic. The reference to the National Interest is available as a backlink to the original source.