Board Thread:General Discussion/@comment-27581425-20170311225357/@comment-27581425-20170727164858

The word "reached" means that the souls "met" Asgore. Toby doesn't specify the place where they "met" and "reached" Asgore, this theory tells that they "met" and "died" to Asgore in different places, cause in the game Gerson said that if you wait long enough Asgore loves to wander around and would eventually met them, this supports the placement of their items.

Ruins, Snowdin, Waterfall, Hotland and Mtt Resort

More to support they didn't die in the barrier is their items scattered throughout. The souls wouldn't last long enough if their items are there.