great market for the central and eastern regions of it. When the Islamic call appeared, the Messenger Muhammad sent Al-Ala bin Abdullah Al-Hadrami in the seventh century AD corresponding to the eighth year of the Hijri to invite the people of Hejir to Islam, which they accepted. Islamic times Eastern Arabia was conquered by the emerging Rashidun Caliphate during the 7th century. It was later inherited by the Umayyads and Abbasids. In 899 A.D., the region came under the control of the Qarmatian leader, Abu Tahir al-Jannabi, and was declared independent from the Abbasid Caliphate of Baghdad. Its capital was at al-Mu'miniya near modern Hofuf. By circa 1000, Al-Hasa became the 9th largest city worldwide supporting 100,000 inhabitants. In 1077, the Qarmatian state of Al-Ahsa was overthrown by the Uyunids. Al-Ahsa subsequently fell under the rule of the Bahrani dynasty of the Usfurids, followed by their relatives, the Jabrids, who became one of the most formidable powers in the region, retaking the islands of Bahrain from the princes of Hormuz. The last Jabrid ruler of Bahrain was Muqrin ibn Zamil. In 1521, the Portuguese Empire conquered the Awal Islands (the islands that comprise present day Bahrain) from the Jabrid ruler Muqrin ibn Zamil, who fell strongly in battle. The Jabrids struggled to maintain their position on the mainland in the face of the Ottomans and their tribal allies, the Muntafiq. In 1550, Al-Ahsa and nearby Qatif came under the sovereignty of the Ottoman Empire with Sultan Suleiman I. Al-Ahsa was nominally the Eyalet of Lahsa in the Ottoman administrative system, and was usually a vassal of the Porte. Qatif was later lost to the Portuguese. The Ottomans were expelled from Al-Ahsa in 1670, and the region came under the rule of the chiefs of Banu Khalid tribe. Al-Ahsa, along with Qatif, was incorporated into the Wahhabist Emirate of Diriyah in 1795, but returned to Ottoman control in 1818 with an invasion ordered by Muhammad Ali of Egypt. The Banu Khalid were again installed as rulers of the region but, in 1830, the Emirate of Nejd retook the region. Direct Ottoman rule was restored in 1871, and Al-Ahsa was placed first under Baghdad Vilayet and with Baghdad's subdivision Basra Vilayet in 1875. In 1913, ibn Saud, the founder of modern Saudi Arabia, annexed Al-Ahsa and Qatif into his domain of Najd. Al-Ahsa has been inhabited since prehistoric times, due to its