This is difficult to answer because the definition of "terrorism" changes over time. I was recently doing some research on the ban on pinball machines in and around Chicago because the mafia were using them as fundraisers. Several Chicago Tribune articles described mobsters and other criminals as "terrorists". But if you look at the dictionary.com page on "terrorist" and check out the paragraph on etymology a little ways down, it says that the modern definition began in British Palestine in the mid 20th century.