User blog comment:Egyptian Hybrid/Can the other three horsemen be considered primordial?/@comment-3423279-20170309054746/@comment-1975828-20170309060504

When was this explicitly stated?

Only Death has stated his own age, being as old as God. No other Horseman has made a reference to his own age. They just call each other "brothers".

If we try to assume whether or not War, Famine and Pestilience are Primordials, it'll just become speculation. Unless stated out loud, it's best to leave only seven primordials (aka characters confirmed to pre-date the Universe).