Millennial Cultivator is a Manga/Manhwa/Manhua in english language, manhua series, english chapters have been translated and you can read them here. You are reading chapters on www.mgeko.cc fastest updating comic site. The Summary is

[This person has obviously been cultivating for millions of years.] Since time traveling, the transmigrator Ye Fan has been living in seclusion in Tianwu City with the intent of living a worry-free life, until one day he awakened to his millennia of cultivation. While others feign at advanced cultivation, Ye Fan acts as though he knows nothing of it.