On 23 December 1936, the Société nationale des constructions aéronautiques du Nor (SNCAN) was officially formed, grouping together five French aircraft factories; further amalgamations into SNCAN soon took place, including Potez in early 1937. Shortly following its establishment, SNCAN received a provisional order letter for ten experimental aircraft; four of these were derived from the Potez 630, three from the Potez 631 (one being the existing 631-01 prototype), two Potez 633 light bombers and one Potez 637 aerial reconnaissance aircraft. This was promptly confirmed by a contract, under which one Potez 633 was replaced by a single Potez 637 low level ground attack aircraft.