Tabia (present-day Buyuk Nefes) was in the eastern part of Galatia, well to the east of the River Halys; Barrington Atlas map 63 grid F1. Capital of the Trokmoi/Trocmi, who settled in this area after the Gallic migration of the 260s BC. Mentioned by Strabo 12.5.2 as a fortress, an emporion, and a place of refuge (in the precinct of Zeus with its colossal bronze statue).
However [NF], it is possible that the place intended was Tabai/Gabai (Isfahan in modern Iran), a place confusing to ancient geographers.
There is also a Tabai in SW Turkey.
[1] The import of this unusual (though cf. delta 335, omicron 707) dual classification is unclear. (Adler reports only 'city' in the Ambrosian Lexicon.)