The Bahçelievler settlement appears to have consisted of a single stratum, corresponding to the Classic Fikirtepe phase of the Late Neolithic.

Within its enclosing walls, and especially at its "foot" by the lower town, a number of late Byzantine (i.e. 13th/early 14th centuries) and early Ottoman ceramics have been found among the stone blocks and glass fragments.

[5]: 461–2  Also, at the Çiftlik Alanı site west of Bilecik proper, Efe et al. reported the presence of unspecified Byzantine material.

)[6][7] According to Aşıkpaşazade's semi-legendary account, Osman I captured the fortress of Bilecik in 699 AH (1299-1300 CE), and the town thus became part of the nascent Ottoman Empire.

Bilecik is sometimes identified, based on a vague phonetic resemblance, with the attested Byzantine village of Belokomis which is mentioned as being captured by "Atman" (Osman) in 1304, but Klaus Belke dismisses this as geographically impossible.

Bilecik has been nominated as the most irrelevant province in the popular Turkish internet dictionary Ekşi Sözlük.

Bilecik consists of the quarters Pelitözü, Aşağıköy, Osmangazi, Orhangazi, Cumhuriyet, Gazipaşa, Ismetpaşa, Istasyon, Istiklal, Beşiktaş, Hürriyet, Bahcelievler and Ertuğrulgazi.