Albert Barnes Commentary 1 Chronicles 4:43

"And they smote the remnant of the Amalekites that escaped, and have dwelt there unto this day." — 1 Chronicles 4:43 (ASV)

Unto this day - These words are probably taken from the record which the writer of Chronicles had before him and do not imply that the Simeonites remained undisturbed in their conquests until after the return from the captivity. See 1 Chronicles 4:41.