n. 25B6; adjective
ancient civilizations : OF LONG AGO, early, prehistoric, primeval, primordial, primitive; poetic/literary of yore; archaic foregone.
an ancient custom : OLD, very old, age-old, archaic, antediluvian, time-worn, time-honoured.
I feel positively ancient : ANTIQUATED, aged, elderly, decrepit, antediluvian, in one's dotage; old-fashioned, out of date, outmoded, démodé, passé; informal out of the ark; Brit. informal past its/one's sell-by date.
archaeo-, palaeo-.
recent, contemporary.