Arabistan
The Arabs of Khuzestan are not indigenous to the province. Most Arabs such as the Bani Kaab tribe, came from the west and southwest of the Tigris and Euphrates outside of Khuzestan, beginning in the 15-16th centuries.
In 1441, Muhammad ibn Falah, founder and leader of the Msha'sha'iya, initiated a wave of attacks on Khuzestan, and the cities of Hoveizeh, Khorramshahr, Ahvaz, Susa, and Dezful started seeing large increases in Arab populations. The term Arabistan thus came into use to refer to the Arab populated areas of this region. At this time, many texts started using both Khuzestan and Arabistan as the region's name. Examples are Majalis Al-Mumineen written by Ghadhi Nurollah Shushtari in 1585, Giti Gosha by Mirza Muhammad Sadigh Musawi, Nasikh Al-Tawarikh by Lisan Malek Sepehr, Muntazam Naseri and Mar'at ul-Baladan by Sani al-Mulk, Sharh Waghi'a by Ismail Mirza Dorughi, and the Afsharid era work Jahan goshay-i Naderi. The Safavid era account Tarikh 'Alam Aray-i Abbasi speaks of dispatching troops to "Khuzestan wa Arabistan" during the 8th year of Shah Abbas' reign.
The name Arabistan, however, became more prevalent over time as the British became gradually involved in the Persian Gulf region. By the time of the Qajar Mozaffareddin Shah, the name Arabistan was meant to completely refer to all of Khuzestan.
With the centralized Pahlavi government of Iran gradually strengthening, Reza Shah restored the name of the province to its original in 1923.
Read more about this topic: Origin Of The Name Khuzestan