Maurya is the name of the dynasty and its founder. The plural is Mauryas. Mauryan is the adjective. Mauryans is not a proper word.
For comparison: Ptolemy, Ptolemies, Ptolemaic, but not Ptolemaics.
Also corrected a single instance of “Seleukus I” into “Seleucus I” for consistency.
Update: and included Kush in identity listOr Gupta, Guptas, Guptan.