The spelling 'Kedrosia' is used by the Suda, Diodorus Siculus and Agatharchides. Most other authors, including Strabo, Claudius Ptolemy and Stephanus of Byzantium spell it 'Gedrosia'.
The term normally describes a chora/territory, not a city. If a city is meant, it is likely to be the ancient capital of at least the western part, the ancient Poura, probably at or near modern Pura.
Kedrosia/Gedrosia was west of the lower Indus valley, roughly the same as modern Baluchistan in present-day Pakistan/Afghanistan/Iran. Large stretches of it were (and are) desert through which Alexander the Great famously marched his army on their return from India.