The title of Khawarazmshah was an ancient title, probably dating to the late Sasanian period, where the region of Khwarazm (the plain south of the Aral Sea/Lake Khawaraz) was ruled by an independent dynasty. The title had continued through several dynasties, among the most famous being the Ma’mounids who ruled under Samanid suzerainty and patronized luminaries such as Abu Rayehan al-Biruni. Under the Seljuks, however, a former Turkic slave of Alp Arsalan, named Anush Tigin, became the governor of Khwarazm, and took the formal title of Khawarazm Shah. Consequently, it is the descendants of Anush Tigin who are the most well-known line of the Khwarazmshahids.
The chaos created by the wars of succession following the death of Malek Shah I the Great Seljuk resulted in a relative autonomy for Qotb ol-Din Mohammad, the son of Anush Tigin. He, however, remained loyal to Mohammad II and Sanjar and protected the north-eastern frontiers against the nomadic invasions. His son, Ala’ ol-Din Atsiz, was involved in several rebellions against Sanjar, while the advance of the Kara Khitay Yelu Dashi eventually made him a vassal of the Kara Khitay. Atsiz, the real founder of the Khwarazmshahids, died in 1156, leaving the throne to his son, Il Arsalan.
Il Arsalan decided to strengthen his rule by taking over Samarqand and other parts of Transoxiana. He was, however, roundly defeated in 1158 and forced to retreat to his capital of Urganch. His further efforts to advance into Khorasan were partially successful, eventually establishing his rule in parts of northern and western Khorasan. However,a Kara Khitay expedition in 1172 confined him to Khawarazm where he died, leaving the throne to his son Takesh.
Takesh’s rule started with a long struggle with his brother, Sultan Shah, who had been restored to his principality in Khorasan. Takesh spent his time trying to confine his brother to Khorasan, while at the same time conducting campaigns against both the Kara Khitay and the Kara Khanids of Samarqand. In 1193, when Sultan Shah died, Takesh became a ruler of Khorasan as well, and a year later, defeating the Seljuk Tughril III, became the ruler of Isfahan and central Iran. He was confirmed in the position as the king of Transoxiana, Khorasan, and Jibal, as well as Iraq, by the Caliph al-Nasir-lid-din-i-llah, to who he paid homage, but was in fact completely independent of. Takesh died in 1200, leaving a vast empire to his son, Qotb ol-Din Mohammad.
Qotb ol-Din Mohammad II was an energetic king who continued his father’s expeditions, conquered southern Iran, and reached the Persian Gulf. Facing opposition from the Caliph, he marched on Baghdad, but his army was caught in snow-storms in the Zagrod Mountains and had to return to Khwarazm, an event that led him to change his title to Ala’ od-Din Mohammad II. He remained, however, the powerful king of all of Iran and Transoxiana, and ruled from an increasingly glorious capital in Urgench. Internally, his court was the scene of competition between the relatives of his first wife, and the mother of his eldest son, and those of his second wife, the Qibchaq noble woman, Tarkan Khatoun. The Qibchaq faction, having gained power, managed to appoint many rulers related to Tarkan Khatoun, to the governorship of the border cities of the Khwarazmian Empire. One of this, Inalchiq, in 1218, through massacring the envoys of the newly established Mongol rulers, Chingiz Khan, initiated an invasion of the Mongols that was to destroy the Khwarazmian Empire and change the socio-political face of Eurasia.
The invasion of Transoxiana by the Mongols, and the capture and destruction of Samarqand, Bokhara, and Urgench, set Mohammad II into flight. Taking refuge in the Caspian island of Abskun, Mohammad tried to form a resistance against the invading Mongols, while at the same time dividing his empire among his three sons, Jalal ol-Din Mingburnu, Ghiyas ol-Din Pirshah, and Rokn ol-Din Ghursanji, ordering the latter two to follow the orders of Mingburnu. Mohammad II himself was assassinated in 1120 in Abskun, leaving his son Mingburnu to resist the Mongols.
Mingburnu was a brave, if cruel and tactless, commander. He had to flee to the east in order to gather troops against the Mongols. His expeditions in Khorasan were quickly defeated, forcing him to flee to India. An important episode on the banks of the Indus recalls Mingburnu losing all of his troops, and crossing the river on his horse alone, while Chingiz Khan was ordering his troops to respect the refugee. While mostly legendary, the episode shows the position of honor that Mingburnu occupies in Iranian historiography. In reality, he was denied asylum by the Sultan of Delhi, who because of his relations with the Caliphate of Baghdad, himself pursued the refugee Khwarazmshah.
In 1223, Mingburnu returned to Iran, trying to establish a kingdom in the central region of Jibal, and conquering as far north as Tabriz. His renewed activities, as well as his provocative action against the Mongol interests in Khorasan, initiated a new wave of Mongol attacks. In 1223, he was defeated in central Iran and had to retreat to Khorasan. By 1225, the Mongols had followed Mingburnu to Tabriz and had driven him to the Caucasus, where he attacked and destroyed many local churches of the Armenians and Georgians, creating a deep local hatred. Mingburnu was forced to flee to Eastern Anatolia, were he clashed with the Seljuks of Rum and the Ayyubids. His temporary successes in establishing a base of power was put to rest through a defeat in Erzinjan, in 1230, at the hands of Kay Qubad I, the Seljuk king. He escaped to Diyarbakir, where he was assassinated by brigands, putting an end to the Khwarazmshahid Dynasty.