This task is about reading the given passage and construct a question about the information present in the passage. Construct a question in such a way that (i) it is unambiguous, (ii) it is answerable from the passage, (iii) its answer is unique (iv) its answer is a continuous text span from the paragraph. Avoid creating questions that (i) can be answered correctly without actually understanding the paragraph and (ii) uses same words or phrases given in the passage.
Q: Proto-Iranian thus dates to some time after Proto-Indo-Iranian break-up, or the early second millennium BCE, as the Old Iranian languages began to break off and evolve separately as the various Iranian tribes migrated and settled in vast areas of southeastern Europe, the Iranian plateau, and Central Asia.
A:
Where did early Iranian people establish societies?