Tigrinya

dəro - before, formerly, earlier, in ancient days (TED 2075)

Probably related following Leslau 1956: 247 and EDG 218.

PS
*dawr-/*dawar- - period, cycle (DRS 240, Marassini 1971: 48, Fronzaroli 1965: 143, 148, EDA II)

The – apparently iconic (descriptive) – reduplication *dār- dār- (or *dār- dawr-), attested in both Akkadian and early NWS (Ugaritic, Hebrew, Aramaic), may go back to PS.