The settlement is divided into several periods, with habitation of later periods occurring higher up the mound on top of the remains of the earlier periods.
Level IV. The first habitation. Writing was not used at this time.
Level III. Another illiterate period of occupation.
Level II, 1920 BC - 1840 BC. During this period Assyrian merchants established themselves in a ring of settlement surrounding the city. They did not conquer it, but paid taxes to the local prince for the privilege of conducting a profitable trade. The city was destroyed by fire in 1840 BC, with the inhabitants leaving most of their possessions behind for the benefit of future archaeologists. The findings have included enormous numbers of baked clay tablets, contained in clay envelopes stamped using cylinder seals. The documents record common activity such as trade and legal arrangements and a few works of literature. They are the oldest written documents from Anatolia.
Level Ib, 1798 BC - 1740 BC. After an interval of abandonment the city was rebuilt over the ruins of the old and again became a prosperous trade center. However it was destroyed again by fire in 1740 BC.
Level Ia. The city was reinhabited but there were no longer Assyrians in residence. The culture was of early Hittites.