Middle Ages 
The Arabs were migrating into the Near East from the 9th century BCE. In the 3rd century CE parts of southern Mesopotamia had a substantial Arab population. Under the Sassanid Empire, southern Mesopotamia was sometimes called Arabaya. The first historical Arab kingdom outside Arabia, Hīra (4th-7th centuries), in southern Iraq, was a vassal of the Sassanids, whom it helped in containing the nomadic Arabs to the south. The Lakhmid rulers of Hīra were recognized by Shapur II (337-358).
Hīra was either Christian or strongly influenced by Christianity, and was a diocese of the Syriac Church of the East between the 5th and 11th centuries. The Sassanid Emperor Bahram V won the throne with support of Mundhir I, Lakhmid Prince of Hīra, in 420.
In 531, the Sassanid Persians defeated the Byzantine general Belisarius at the Battle of Callinicum, south of Edessa (southeastern Turkey), with the help of Hīra. In 602, Khosrau II deposed Nu'man III of Hīra and annexed his kingdom. Islam overran the Sassanid Empire in the 7th century.
From ca. 527, Hīra was opposed by the Ghassanids, a Byzantine-sponsored Arab tribe resident in Syria and Palestine. The two Arab powers engaged in a long conflict of their own, which also functioned as a proxy war for their respective imperial suzerains.
Spread of Islam 
Following the Siege of Hira, the city was captured by Muslim army of Rashidun Caliphate under the command of Khalid ibn Walid in May 633.Adi Bin Hatim, the deposed King of Tai (south of al Hira) visited Muhammad, The Prophet of Islam and was told by Muhammad that,
- “I swear by the One who has my soul in His Hand, Allah will complete this affair, until a woman travels from al-Hira to make Tawaf around the Ka’bah in Makkah, without fearing anyone. You will seize the treasures of Kisra bin Hurmuz. If you live long, you would see a man offering a handful of gold or silver to others but none will accept it.”
The meaning of thi entailed that Islam would one day become so strong that a woman would be able to travel from al-Hira to Makkah without a male guardian and without any need for protection. She would pass by hundreds of tribes and no one would dare to harm her or take her wealth. This is because the Muslims will become so strong that no one would dare to trouble a Muslim from fear of other Muslims rushing to his or her help. Adi then accepted to be Muslim.
Adi Bin Hatim later said,
- “I have seen a woman riding a camel travelling from Al-Hira till it made Tawaf around Ka‘bah fearing none but Allâh, I have also been one of those who opened the treasures of Kisra bin Hurmuz. I swear by the One who has my soul in His Hand, the third prophecy will also be fulfilled, since Allah’s Messenger has said so!” (Collection from Hadith in Books of Muslim and Ahmad)
See also 
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