predominance vs ascendency

predominance and ascendency both are nouns.

Word	Noun	Adjective	Verb	Adverb
predominance	Yes	No	No	No
ascendency	Yes	No	No	No

As nouns, ascendency is a hypernym of predominance; that is, ascendency is a word with a broader meaning than predominance:

predominance: the state of being predominant over others
ascendency: the state that exists when one person or group has power over another

Other hypernyms of predominance include ascendance, ascendancy, ascendence, control, dominance.

predominance (noun)	ascendency (noun)
the quality of being more noticeable than anything else	the state that exists when one person or group has power over another
the state of being predominant over others