The Proto-Indo-European tense system made a distinction between the aorist – referring to events that had been completed before the moment of speaking, the imperfect – referring to events that lasted for a given period of time before the moment of speaking, and a synthetic perfect – referring to events that occurred in the past, but are relevant at the moment of speaking. Subsequently, an analytic perfect developed, which, throughout Europe and especially in its central parts, has been ousting out the other past tenses and taking over their functions. In the Balkans, however, the analytic perfect, with functions distinct from the aorist and the imperfect, coexists with the latter two tenses, though the spread and use of these tenses and their interrelationship are different in different Balkan languages.