Sheikh Ubeydullah (1826–1883), also known as Sayyid Ubeydullah, was the leader of the first modern Kurdish nationalist struggle. Ubeydullah demanded recognition from the Ottoman Empire and Qajar Iran authorities for an independent Kurdish state, or Kurdistan, which he would govern without interference from Ottoman or Qajar authorities.

Sheikh Ubeydullah was an influential landowner in the 19th century and a member of the powerful Kurdish Shamdinan family from Nehri. He was the son of Sheikh Taha and a nephew to Sheikh Salih, from whom he inherited the leadership of the Sunni Sufi Naqshbandi order in Shamdinan. He united the various Kurdish tribes of the region to begin his rebellion against both the Ottomans and Qajars. After his rebellion was suppressed, he was exiled first to Istanbul, then to Hijaz where he died.

Sheikh Ubaydallah was born 1826 in Nehri, then Kaza of Şemdinan, Van Eyalet, Ottoman Empire. The village is now Bağlar and is located in the Nochiya region. The family owned large estates with 200 villages in the Ottoman Empire and Iran. They cultivated tobacco. Ubeydallah's descendants today bear the surname Geylan. He came from an influential family of spiritual leaders. The family traced its ancestry back to Abdul Qadir Gilani, the 11th-century founder of the Qadiri order, and ultimately to the Prophet Muhammad. As descendants of the Prophet, they bore the title of Sayyid. Abdul Qadir Gilani‘s son, Abdulaziz, migrated to Akre, north of Mosul. His descendants migrated further north toward Hakkari. Mullah Saleh then settled in the village of Nehri. With the spread of the Naqshbandi in the Kurdish regions at the beginning of the 19th century, the family also changed their order and became members of the Naqshbandi order.

Sheikh Ubaydalla's father was Sheikh Sayyid Taha, who succeeded his uncle Sheikh Abdullah as the leading sheikh. As a sheikh, Sheikh Sayyid Taha had great influence over the Kurds in the border region of the Ottoman Empire and Iran. After his death, he was succeeded by his brother Saleh. Ubaydalla himself succeeded his uncle Saleh.

The American missionary Joseph Cochran characterized Ubeydallah as a charismatic, deeply religious, and upright person. S. G. Wilson described him as the most important religious leader among the Sunni Kurds. He had a solid theological education and was a connoisseur of Arabic and Iranian literature.

Sheikh Ubaydalla exercised his temporal power with great authority. He punished lawbreakers harshly and harbored a dislike for Turkish and Iranian officials.

The emergence of Islamic scholars and leaders, or Sheikhs, as national leaders among the Kurds was the result of the elimination of hereditary semi-autonomous Kurdish principalities in the Ottoman Empire, especially following the Ottoman centralization policies of the early 19th century. Sheikh Ubeydullah was one of several religious leaders who were there to fill the void and reestablish a sense of lawfulness in the former principalities that had been since left to feuding chieftains. Despite previous revolts by Kurdish leaders to reassert control over territories, mainly their own former principalities, Sheikh Ubeydullah is regarded as the first Kurdish leader whose cause was nationalist and who wished to establish an ethnic Kurdish state.

Sheikh Ubeydullah was from an already powerful family, the Şemdinan from the region of the same name – Şemdinan – who owned considerable amounts of land in the Kurdish areas of the Ottoman Empire. During the Russo-Turkish War in the late 1870s, Ubeydullah led the Kurdish tribal forces, defending the Ottoman Empire against the Russians. In the aftermath of the war, he filled a political vacuum left by the devastation in the area and assumed the Kurdish leadership in the region.