The Relief of Qasr al-Bahili was the successful relief of the Arab garrison of the small fortress of Qasr al-Bahili from the siege by the Turkic Türgesh Khaganate. Sent by the Umayyad Caliphate's governor of Khurasan, an Arab relief force under al-Musayyab ibn Bishr al-Riyahi managed to break the siege and escort the garrison to safety in Samarkand. The siege marked the beginning of the Türgesh invasion of Transoxiana, which the Arabs had only recently subdued, and which became a battleground between the two empires for the following two decades.