There’s another advantage of cavalry over chariots - the number of active combatants. A unit of cavalry had 1 combatant rider per horse, but each chariot needs a driver, reducing the number of effective fighters. For ex. a 2- horse chariot has 1 driver and 1 combatant, effectively half as many as an equivalent number of cavalry horses with a combatant rider on each. Even if we’re generous and assume that the driver can use a shield or do something to help defend the chariot, it is a less efficient method of using horses in combat than cavalry, and that’s before taking into account the added expense in material and labour of maintaining the chariot (compared to the tack needed for a cavalry horse). The chariot itself may have had some psychological impact on enemies (ex Caesar’s soldiers encountering Celtic chariots) or physical utility (heavy or scythed chariots), but those don’t seem to have offset the overall greater efficiency of using the horses for cavalry. So, by about 600 BCE in Europe and Western Asia chariots were largely abandoned, except as an occasional showpiece for commanders to use, or in specialized roles or in marginal areas.