The Sykes-Picot Agreement was a secret agreement signed by the British and French governments in 1916 during World War One. It aimed to divide the Ottoman Empire`s territory in the Middle East between the two countries, with Russia receiving some territories as well.

The agreement caused controversy among Arab nationalists who had been promised independence in exchange for supporting the Allies during the war. The Sykes-Picot Agreement contradicted these promises and instead established French and British spheres of influence in the Middle East.

The agreement became public knowledge in 1917 when it was leaked to the press. The revelation caused outrage among Arab nationalists who saw it as a betrayal of their trust.

Despite the controversy, the Sykes-Picot Agreement remained in effect until the end of World War One in 1918. However, its influence can still be felt in the modern-day borders of several Middle Eastern countries.

The agreement effectively divided the region into new states with arbitrary borders that did not take into consideration the ethnic, cultural, and religious diversity of the area. This resulted in conflicts and tensions that continue to this day.

In conclusion, the Sykes-Picot Agreement ended in 1918 at the conclusion of World War One. However, its long-lasting impact has been felt throughout the Middle East with the region still grappling with the consequences of its arbitrary borders and disregard for the local cultures and ethnic groups.