Following is a chronology of events in Turkey's bloody Kurdish insurgency:
1920: The Treaty of Sevres, signed between the Ottoman Empire and Allied forces, envisages the creation of a Kurdish state. Plan is annulled after Turks win "Independence War."
1923: The Treaty of Lausanne establishes the boundaries of Turkey and spreads the Kurds among several nations.
1920-1937: Several Kurdish rebellions for independence are subdued by force, resulting in the deaths of thousands of people.
1937: Turkey, Iran, Iraq and Afghanistan sign the Treaty of Saadabad to coordinate their action against insurgent Kurds.
1978: Abdullah Ocalan founds the Kurdistan Worker's Party (PKK) for an independent Kurdish state.
1984: The PKK takes up arms against Ankara, waging a war in the Kurdish-majority southeast and larger Anatolia region.
1987: Ankara puts 11 provinces under a state of emergency rule, increasing the military initiative in the southeast.
1991: The Gulf War paves the way to de facto autonomy for Kurds in northern Iraq. Attacks inside Turkey launched from the other side of the shared border increase.
1992: The Turkish army mounts a vast air and land operation against bases of the PKK in northern Iraq.
1995: Turkish incursion inside Iraq involving more than 30,000 troops. Army crackdowns in Turkey's southeast increase.
1999: Ocalan is captured in Kenya and sentenced to death for treason.
2002: Ocalan's death sentence is commuted to life imprisonment as Turkey abolishes the death penalty.
2004: Ankara allows limited Kurdish language in state television broadcasts.
2004-2007: The PKK increases ambushes and bomb attacks.
2007: Turkey's parliament allows the army to stage cross-border operations against Kurdish rebel hideouts in northern Iraq.
2009: The Turkish government announces a "Kurdish initiative," a package that seeks increased rights for the minority, triggering a nationalist backlash. Police round up hundreds, including activists, journalists and politicians, suspected of ties to the PKK.
April: Turkish Prime Minister Recep Tayyip Erdogan pays a landmark trip to Iraqi Kurdistan.
September: A news agency releases voice recordings of failed peace talks held secretly between the intelligence agency and senior PKK officials in Oslo.
October: Twenty-four Turkish soldiers are killed in one of the deadliest Kurdish rebel attacks in years.
December: Thirty-four civilians, mistaken for rebels, are killed in a botched Turkish airstrike near the Iraqi border.
September: Hundreds of Kurds in prisons launch a hunger strike, demanding language rights and better conditions for jailed Ocalan.
December: Ankara acknowledges nascent peace talks between the secret services and Ocalan with the goal of disarming the rebels.
January: Two Kurdish lawmakers pay a landmark visit to Ocalan in prison.
Three Kurdish activists, including PKK co-founder Sakine Cansiz, are shot dead in Paris.
Turkey allows the use of the Kurdish language in court.
February 23: A second delegation of Kurdish lawmakers visit Ocalan on his prison island as part of the new peace efforts.
March 13: Kurdish rebels free eight Turkish prisoners in response to the peace push.
March 21: Ocalan calls for a ceasefire in a letter issued to mark Kurdish New Year, telling militants to lay down their arms and leave Turkish soil.