The economy of Qatif witnessed a sharp decline in the 1920s, initially due to the invention of cultured pearls which severely impacted the Gulf pearl trade, then due to World War I. The decline was accelerated by a special "Jihad" tax imposed by the Saudis (then the Sultanate of Nejd), which was used to fund military campaigns. The economic situation became so dire that many citizens were imprisoned for unpaid taxes, including several wealthy landowners and merchants. Then in 1929, the tax was doubled. Riots broke out in several towns, and a large group escaped to Bahrain and requested protection from the British consul. The governor of Qatif responded with intimidation and mass imprisonments. Several notables wrote letters to King Abdulaziz voicing their complaints. He eventually met with the governor and some citizens, pardoned past-due taxes, and reduced new taxes.