1
general::
Since long ago; for a long time. For example, This painting has been in the family from way back, or We know the Smiths from way back. [Colloquial; late 1800s]
American Heritage Idioms
2
general::
Phrase(s): from way back
from far in the past; from a much earlier time. • Grandfather comes from way back. • This antique clock is from way back.
McGrawhill's American Idioms And Phrasal Verbs