The term 'had foundation' is a phrase used to indicate that something or someone had a strong basis or groundwork on which they were developed or built. Some synonyms for 'had foundation' are 'was established on,' 'had its roots in,' 'derived from,' 'was based on,' 'had its origin in,' 'stemmed from,' 'had a basis in,' 'was grounded in,' 'had its beginning in,' 'had its underpinnings in,' 'was rooted in,' 'had its footing on,' 'had an undercurrent of,' and 'owed its existence to.' These synonyms can be used interchangeably with 'had foundation' to indicate that something or someone has a firm starting point or core foundation.