Without trying to politicize this post, it's pretty well known most countries with a significant Kurdish population (Turkey, Iraq, etc.) seem to harbor some serious ill feelings toward them. What have they done or what events in history have lead to this point?
Also I apologize if this is directed at too recent and modern of a topic for this sub, but I don't know where else to go and this sub is known for it's incredibly in-depth and insightful answers, and I'm wondering if there's some historical events that have lead to this current general sentiment in the region.
Since the Kurdish population extends from Turkey, Syria, Iraq, and Iran (and very small parts of Armenia), there will be a lot to talk about. I will focus on Iran since they have an unique history and relationship with the Pahlavi Dynasty (1925-1979) and the Islamic Republic (1979-Present).
Before I hop into your question, an important clarification must be made: who are the Kurds? The Kurds are a group of people entirely distinct from Iranians (Persians) and Arabs. They trace their history to the Medes of the seventh century BC, but they are thought to be descendants of the Carduchi, who possesses ethnic differences from the Arabs, Persians and Turks. They have a very distinct language (Kurdish) that is perhaps closest to Farsi. Most Kurds are Sunni Muslims but a significant number are also Sufis. Although there are an estimate of around 27 million Kurds, they have always been a minority because they are spread out between four countries. Keeping this in mind, long periods of alien occupation led to frequent rebellions, especially during the Qajar Dynasty and Ottoman's rule over Turkey, Syria and Iraq.
In Iran, the Kurdish areas (North-West of the country) served as a strategic value as their land is between the highway between the "West" and the "East." During World War II, the Soviet Union attempted to create a Kurdish "republic", with intentions of incorporating it into the Soviet republic of Azerbaijan; but this failed as the United States and Western Allies pressured Moscow to withdraw from Northern Iran after the war ended. With the Soviets out of Iran, the Iranian government was in the position to dismantle the Kurdish rebels by initiating a "cultural cleansing" operation in December 1946. This cultural cleansing banned teachings of Kurdish language, closed down Kurdish newspapers and destroyed Kurdish books. The leader of the Soviety for the Revival of Kurdistan, the Komelei Jiyanew-e Kurdistan, Qazi Muhammad, was captured and hanged in March 1947. Not all Kurdish fighters were captured and most of them fled to Iraq (who then also led an insurgency against the Iraqi Ba'athist government, which is another story to tell!). The resentment of the cultural cleansing operation by the Pahlavi Dynasty left a bitter taste in the Kurdish community.
As we head deeper into the Cold War, Iran and Iraq constantly exploited the Kurdish population by supplying the other Kurdish population - Tehran supplied Iraqi Kurds to cause problems in Northern Iraq and Baghdad in the Kurdish Iranian provinces. For example, Mohammad Reza Shah Pahlavi went as far as sending Iranian troops into Northern Iraq to "liberate" the Kurds against Saddam Hussein in January 1975. In comparison, Iraq was in a weaker position as the unrest caused by Iraqi Kurds made it far more serious than the Iranian Kurdish question. During the Iran-Iraq war, the Islamic Republic did not directly aid the Kurds in direct military operations until 1985, and despite Tehran's appeals, the Kurds refused to mount conventional offensives and resorted to guerrilla warfare. The Iranian Shia population as well as the Sunni Kurds, in a sense, became wary of each other as neither ethnic groups trusted each other.
In the Iranian Islamic Republic, this is where it gets interesting. Iran is the country where Sunni Kurds had to deal with a Shiite majority. Just to make a quick note, Sunni Islam is the largest unrecognized religious minority in modern day Iran, and the combination of being a Sunni Muslim and a Kurd spells disaster. The creation of the Islamic Republic in 1979 immediately caused violence in various Sunni dominated provinces in Iran. Shaykh 'Izz al-Din Husayni, the influential religious leader of the Mahabad Kurds, allied himself with the powerful and radicial left by adopting a socialist discourse that emphasized self-determination for ethnic minorities. In 1980, Ayatollah Khomeini announced that he was prepared to guarantee Sunni minority rights and to allow the Sunnis to have their own religious courts in areas where they constituted the majority, in an attempt to get Sunni minorities to participate in the 1980 presidential election. Shaykh 'Izz al-Din and other Kurdish leaders rejected this proposal, who opposed Khomeini's theory of government vilayat-e faqih and argued "in Sunni Islam there is no Imam as political leader." Overe time, leadership would pass from these Kurdish religious figures to secular Kurdish politicans. When the Islamic Republic sent its army to take control of Kurdistan, there were only short-lived Sunni Kurdish resistance movement, but only secular forces remained in place. In the Parliament of the Islamic Republic (Majlis), five seats are reserved for recognized religious minorities: two for Armenian Christians, one for Jews, Zorastrians and Assyro-Chaldeans respectfully. Despite the absence of Sunnis in the power structure of the Islamic Republic, they still form a sizable but unstable coalition as the Sunni interests are usually inconsistent.
A huge part of why Kurds are treated differently in Iran (not necessarily hated), is because they are a different ethnic group and historical treatment from the respective state they resided in causes even more distrust. In Iran, their status as Sunni Kurds shuns them from society as they are not only "discouraged" from speaking Kurdish in favor of Farsi, but also encouraged to attend Shiite mosques as no Sunni mosques publicly exist.
Sources:
Aghaei, Samnak. In Kurdistan and Sistan-Baluchistan Provinces Sunni Students Commemorate Ay. Montazeri. Roozonline. 2009.
Dugoignon, Stephane A. Sunnis and Shiites in Iran Since 1979: Confrontations, Exchanges, Convergences. In The Dynamics of Sunni-Shia Relations: Doctrine, Transnationalism, Intellectuals and the Media. Edited by Brigitte Marechal and Sami Zemni. Hurst & Company. London. 2013.
Johnson, Rob. The Iran-Iraq War. Palgrave Macmillan. United Kingdom.2011.
Kamrava, Mehran. The Political History of Modern Iran: From Tribalism to Theocracy. Praeger. Westport, CT. 1992