context: When the Yemeni unity took place, and the second Gulf War followed, and the volume of oil stored in Yemen became clear, the border problem arose again after the agreement on the final demarcation of the border between Yemen and the Sultanate of Oman in 1990, so discussions took place between the two parties in the form of a committee of bilateral experts It started in September 1992, after bilateral consultations took place in Geneva in July 1992 and seven meetings were held alternately between Riyadh and Sana'a.
question: When was the border demarcation agreement concluded between Yemen and the Sultanate of Oman?
answers.text: 1990