originally, name of pagan vernal [spring time] festival almost coincident in date with paschal [passover] festival of the church... [from Webster's New World Dictionary]
...from prehistoric WGmc name of pagan spring festival, derived from the root of east. [from Webster's Third New International]
...Eástre, a goddess of light or spring [or dawn], in honor of whom a festival was celebrated in April [from Webster's Revised Unabridged, 1913 Edition]

and 'east' itself is as you say. if the festival is "prehistoric", I don't think we'll get much further back. <g>