Linked from
The 7 pages that link to Bithynia, each with the reason it gives.
Osman INarrower topic: Osman’s frontier principality expanded into Byzantine-held Bithynia.
ArrianBroader topic: Arrian served as Roman governor of this province during his public career.
NicaeaNarrower topic: Nicaea became one of Bithynia's leading cities.
NicomediaNarrower topic: Nicomedia became Bithynia’s leading city and later its provincial capital.