In 1924, the National Council of Iran through an edict from Mohammad Reza Pahlavi officially changed the city's name to Masjed Soleyman.

[6] Negotiations with the reigning monarch Mozaffar al-Din Shah Qajar began in 1901, and with the offer of £20,000 (£2.7 million today),[7] for a sixty-year concession to explore for oil—later, the D'Arcy concession—was secured in May, covering 480,000 square miles (1,200,000 km2), and stipulated that D'Arcy would have the oil rights to the entire country except for five provinces in Northern Iran.

After the D'Arcy concession, the British government became much more concerned with the stability of Iran because of their reliance on the country's vast oil reserves.

[8] Ḥossain Qolī Khan Haft Lang was appointed superintendent (nāẓem) of the Baḵtīārīs by the Shah in 1862 and head of the tribe (īlḵān) in 1867.

[9] This event largely succeeded as a result of the Bakhtari tribal coalition military campaign led by Ali-Gholi Khan, Sardar Asaad II, a chieftain of the Haft-lang tribe and his brother Najaf Qoli Khan Bakhtiari- Saad ad-Daula (also referred to as Samsam-os Saltane) whom in 1909 marched up to the gates of Tehran, and eventually deposed Mohammad Ali Shah Qajar (r.

Nonetheless, with Russian backing, the Shah would attempt to regain his throne in 1911 by landing with a coalition of forces at Astarabad .

In February 1921, the said policy makers instigated a coup by which Reza Pahlavi the commander of the entire Cossack Brigade which was based in Qazvinordered his troops to march towards Tehran and seized the capital.

[13] Reza Shah Pahlavi would eventually execute a few noteworthy tribal leaders to crush Bakhtiari autonomy and maintain control over the tribe.

The British Foreign office selected William Knox D'Arcy, a millionaire investor, and provided him with the reports, promising him greater wealth and governmental support if he invested in the excavation of oil.

D'Arcy agreed and sent out representatives to Tehran to win a concession that would give him the exclusive rights to prospect for oil in Persia.

On 16 April 1901 negotiations commenced between D'Arcy's representatives and the Qajar monarch Mozzafar al-Din Shah over a potential oil concession.

[4] On 28 May 1901, Shah Mozzafar al-Din signed an 18 article concession which exclusively gave D'Arcy the rights to prospect, explore, exploit, transport and sell natural gas, petroleum, asphalt and mineral waxes in Persia.

At 4:00 am on 26 May 1908, commercial quantities of oil were struck at the Masjed Soleyman site and a fifty-foot gusher of petroleum shot up the no.

[22] In April 1909, D'Arcy was appointed a director of the newly founded Anglo-Persian Oil Company (APOC),[15]: 148  which would later become British Petroleum (BP).

[16] The four main tribal divisions of Haft Lang are Duraki, Babadi, Bakhtiarwand, and Dinaruni, who are then divided into lesser clans.