User blog comment:Zippertrain85/The reasons why Serana is not from the First Era./@comment-87.109.65.219-20131226171408

The red mountain's collapse was during I think either 6th century or 7th century of the First Era. When you head to winterhold with Serena, she says 'this play wasn't so crumbly when I was alive, it was an actual city' or something along those lines So yes, I think off of that evidence she is from the first era of before