Base 120 is the largest of the historically attested bases There are references to a long or twelftywise count vs a short or teenty-wise count in all of the early Germanic writings.
teenty
Etymologie
() *ten + -ty
Perhaps from Old English hund-téontiᵹ (compare hund-seofontiᵹ, hund-eahtatiᵹ, hund-niᵹontiᵹ, hund-endleofantiᵹ, and hund-twelftiᵹ for modern seventy, eighty, ninety, and nonstandard eleventy, twelfty, reflecting the old Germanic hybrid base-ten and base-twelve numbering system); perhaps reconstructed based on eleventy etc. and -teen.