During World War I, the Iranian province of Gilan witnessed rise and, after the collapse of Tsarist Russia, domination of the popular armed movement of Ittihiad-i Islam, also known as Jangal movement that sought independence of Iran on the basis of Pan Islamism as well as nationalistic stand points. Despite their success in Gilan, the Jangalis' attempt to penetrate into other regions of the southern shores of the Caspian failed. This study examines the obstacles to expansions of Ittihiad-i Islâm movement to the neighbouring Caspian province of Mazandaran (former Tabaristân) in 1918/1336 A.H. when the movement was experiencing its zenith of purity, popularity and success. The findings demonstrates that in Mazandaran, in spite of existing potentials for revolutionary activities, the Jangalis met with opposition of Ittihad-i Milli of Tabaristân (Pan Tabaristanism), a novel unpopular political organization that claimed autonomy to govern and develop the province. Ittihad-i Milli of Tabaristan, originally a respond to Ittihiad-i Islâm movement, was founded by local large landowners with military ranks and forces. In its short life, Ittihad-i Millī of Ţabaristân successfully prevented penetration of the Jangalis and their ideas not only into Mazandaran but also into the Caspian province of Astarabad. The findings also reveal that Jangalis' pragmatism itself kept Mazandaranian progressive forces and activists aloof from Ittihiad-i Islâm movement.