Well terrorist groups span centuries. The earliest group who were well known as being terrorists would have to be the Jacobians who were at the heart of the French Revolution, they would use terror to sway people to their ideology.
Perhaps more notably are the Crusades of the the 11th and 12th century. These Europeans went right down into the Middle East slaughtering and torturing thousands of innocent Jews and Muslims because of their religious beliefs and ideologies; much like Al Qaeda.
There is of course Hitler in his Holocaust – this is again intolerance of a groups ideology; the Jews. This is like Al Qaeda in the way that they killed thousands of westerners and even their own people. Even though to us it seems like the Jews did nothing wrong, in Hitler’s eyes they were guilty much like how in the eyes of extremists we are guilty.
One of the first attacks on Europeans from the Middle East was the PFLP who were Palestinian terrorists, they hijacked planes and landed them at Dawson’s Field in Jordan. These extremists were quite soft in comparison to todays standards. They held hostages for 6 days then released them once there demands; (prisoners being released) had been met. Then they blew up the planes in a symbol of defiance.
Terrorists groups have been around for centuries and like the examples above many of their motives are unclear. You just have to remember that the motive of a terrorist is to get as much media attention as possible. This is why they challenge the ideals of other people, they more extreme they sound, the more coverage they get and the more people are effected by their message.