part of Lur-i Buzurg became known as Bakhtiyari. Constitutional Revolution: In Iran's contemporary history, the Bakhtiari have played a significant role; particularly during the advent of the country's Constitutional Revolution (1905–1907). This event was largely secured through the Bakhtari campaign, which eventually deposed Mohammad Ali Shah Qajar (r. 1907–1909). The Bakhtiari tribesmen, under the leadership of the Haft Lang khans Sardar Assad and his brother Najaf Qoli Khan Bakhtiari- Saad ad-Daula (also referred to as Samsam-os Saltane), captured Tehran and, as a result, saved the revolution. These events eventually led to the abdication of Mohammad Ali Shah Qajar (r. 1907–1909) in 1909, and his exile to Russia. This incident secured Saad ad-Daula the position of Prime Minister in the period that followed the abdication of the Qajar Shah. Nonetheless, with Russian backing, the Shah would soon return in 1911 by landing with a coalition of forces at Astarabad . However, his efforts to reclaim his throne would bear no fruit. In this sense, the Bakhtiaris played a critical role in saving the revolution from the Qajar forces. Pahlavi Period: With the expansion of Bakhtiari influence, urban elites (particularly in Tehran) began to worry in regards to a potential Bakhtiari takeover of Persia's affairs. Prior to this point, the Bakhtiari had largely remained within their own territorial boundaries. The Bakhtiari influence would continue to play an important role within the early 20th century politics of Iran. Reza Shah Pahlavi (r. 1925–1941) made the destruction of the Bakhtiari influence his mission. The existence of oil on Bakhtiari territory further motivated the Pahlavi monarch to undermine the autonomy of the tribe, and force its population to adhere to the commands of the central government. Reza Shah Pahlavi would eventually execute a few noteworthy tribal leaders to crush Bakhtiari autonomy and maintain control over the tribe. Amongst the executed Khans was Mohammad Reza Khan (Sardar-e-Fateh), whose son later became the Pahlavi Prime Minister Shapour Bakhtiar. The latter event was a turning point for Bakhtiari and their rise within Iranian politics. Tribal structure The Bakhtiari people trace a common lineage, being divided into two branches, Chahar Lang (English: Four Shares) and Haft Lang (English: Seven Shares), each branch being divided into different sub-branches (bāb, tāyefe, tireh, tash, fāmil and owlād). Lang word in bakhtiari dialect means "share of tax or inheritance". The famous documentary Grass: A Nation's Battle for Life (1925) tells the story of