for many years; anciently
Archaic or highly literary adverb meaning 'for a long time' or 'since ancient times'. Not used in everyday speech; encountered mainly in classical texts or poetic language.
A tale has been passed down of people who settled in this land many years ago.
The villagers still remember the legend that has been told for many years.
Compound of 年 (toshi, 'year') and 久しく (hisashiku, adverbial form of 久しい, 'long time'). The exact historical derivation is uncertain, but it follows a classical pattern of forming adverbs.