How many terrorist groups do you think there are in the Syrian conflict? A conservative estimate is 30-35! There are of course the well known ones: The Islamic State, IS or ISIS (IS in Iraq and Syria) or often called ISIL (IS in Iraq and the Levant, where the Levant includes Syria and Lebanon); and the Al Qaeda affiliate Jabhat al Nusra or the Al Nusra Front. But, there are also many local groups on both sides such as: Jaysh al-Muhajireen wa al-Ansar that supports Jabhat al Nusra and Liwa Shuhada’ al-Yarmouk (The Yarmouk Martyrs Brigade) that supports IS and the opposition to Pres. Assad’s regime, and the Ba’ath Brigades and the Palestine Liberation Army that support the regime, together with elements of the Iranian Revolutionary Guard and Hizbollah from Lebanon. Separate from these are the Kurdish groups that form Rojava, the Kurdish Autonomous Region in the north, with its People’s Protection Units (YPG).
A map of the regions of former Syria controlled by all these groups is extremely complex and gives a checkerboard pattern. But, the overall conclusion from such a map is that IS controls the largest part ca. 40% of central and eastern Syria from its capital in Raqqa. The regime forces, including the Syrian Army controls ca. 15%, mostly in western and north-western Syria (the Alawite region) including Damascus. Rojava consists of ca. 15% of Syria, The Free Syrian Army and the so-called Opposition to the regime control ca. 10% in the north and south, while Al Nusra controls ca. 5% of Syria in pockets in the north and south. (For comprehensive lists of the groups and a map of their distribution go to https://en.wikipedia.org/wiki/List_of_armed_groups_in_the_Syrian_Civil_War). Also to see analysis of individual groups see the excellent work of Aymenn Jawad Al-Tamimi of the Rubin Institute of the Inter-Disciplinary Center (IDC) in Herzliya (for example http://www.rubincenter.org/2015/09/jaysh-al-muhajireen-wa-al-ansars-allegiance-to-jabhat-al-nusra/ and other editions of the MERIA Journal).
Into this heady mix come the Russians, adding to the US and its Coalition allies (France, UK, Saudis, Jordan, ec,) who are flying sorties against the IS. But, the Russians are not restricting themselves to only “terrorist” groups in the Western sense, but are also attacking all Opposition forces to the Assad regime as well as civilian targets, according to US sources. In addition, the Turkish Air Force is attacking mainly Kurdish forces, contrary to western interests, which they consider as terrorists and allies of their enemy the Kurdish People’s Party (PKK).
So there are at least 10 distinct forces fighting in Syria (Syria Army, Iran, Hizbollah, Russia, US and Coalition, Kurds, Turkey, IS, Al Nusra, Free Syrian Army and other Opposition Forces), with ca. 300,000 deaths, 7.5 million internally displaced refugees and 4 million external refugees in Turkey, Iraq, Lebanon, Jordan and several hundred thousand of them headed towards Europe. What a mess, and that is not even mentioning Israel.