Texas Hold'em uses the top 5 cards including the board to create the best hand possible for any player, and since both of you had lower kickers than what was present on the board, you used the board to fill that spot of kickers, so both of you had the three of a kind and filled the other 2 cards with the 5 and 9 on the board. So hence the pot was split. You should maybe look into the concept if you don't understand it bud.