"The modern English term Easter developed from the Old English word Eastre, which itself developed prior to AD 899. The name refers to the Eostur-monath, a month of the Germanic calendar which may have been named for the goddess Eastre in Germanic paganism.
"Eostur-monath, qui nunc paschalis mensis interpretatur, quondam a dea illorum quae Eostre vocabatur et cui in illo festa celebrabant nomen habuit."
which translates as:
"Eostur-month, which is now interpreted as the paschal month, was formerly named after the goddess Eostre, and has given its name to the festival."
Some scholars have suggested that a lack of supporting documentation for this goddess might indicate that Bede assumed her existence based on the name of the month. Eostur-monath, and thus, according to Bede, from the Germanic goddess Eostre, though this etymology is sometimes disputed....
Jacob Grimm took up the question of Eostre in his 1835 work Deutsche Mythologie. Grimm notes that Ostara-manoth is etymologically related to Eostur-monath, and in writing of various landmarks and customs that he believed to be related to a putative goddess he named Ostara in Germany."In a recent German-language publication at Efodon Synesis (see here for Der Bodenhimmel der Oesterholzer Mark um die Spitze der Externsteine, which is a much better quality color .pdf version from me), I have pointed out that Ostara as a German priestess was tied to the megalithic, astronomical sites that are found at the Externsteine (Extern Stones), Osterholz and Osnabrück.
The German name for Easter is Ostern. As written by Peter Weinfurth at Oesterholz and Karl Theodor Menke in Verehrung der Eostra an den Externsteinen, Kapitel IX, Geschichte der Externsteine, Ostara or Eostra as a star priestess is tied particularly by legend to the megalithic site of Oesterholz (Oester-holz) near the Extern Stones (see this .pdf of my article on the Externsteine, Sternensteine: Darstellungen frühgeschichtlicher Astronomie am Beispiel der Externsteine).
There is little doubt that Easter as a holiday of the Spring season goes back many, many millennia.