Board Thread:Questions and Answers/@comment-11448255-20180625160751/@comment-33883848-20190831153851

I think so because of those facts:

-Monsters left the ruins to settle the rest of the undeground in the year 201X as Toriel has a calendar from the begining of 201X in her house.

-Asriel was alive during this time as he found Chara the same year and has Toriel's house has a room called "asriel's room"

-Since the monsters colonized the underground in the year 201X ,the CORE that's said to be a source of electricity for the whole underground was likely built arround this time.

-Since the CORE was likely built in 201X by Gaster and that Asriel was already born ,Asriel was likely alive when Gaster was the royal scientist.