Have you ever noticed that specific commandments were given for kings, long before Israel ever had kings? One of their commandments was against multiplying horses:
But he shall not multiply horses to himself, nor cause the people to return to Egypt, to the end that he should multiply horses: forasmuch as the LORD hath said unto you, Ye shall henceforth return no more that way. (Deuteronomy 17:16)
Dake comments on this text on page 217 of The Dake Annotated Reference Bible:
In Scripture the horse is a symbol of fleshly strength and might in war (Job 39:19; Ps. 20:7; 33:16-17; 147:10; Jer. 8:16). God commanded the king of Israel not to put his trust in costly preparations for war (Hos. 1:7), like other rulers. Egypt was the principle source of war horses for western Asia (Ex. 14:5; 1 Ki. 10:28-29; 2 Ki. 7:6). God knew that any alliance with Egypt would cause Israel to depend on them and would reverse His great work of delivering them from bondage to kings. Going back to Egyptian bondage was the final and greatest curse God said would come upon Israel for sin and rebellion; hence He warned them against such an end (28:68). The danger of horses was threefold:
In later times Palestine became the country of horses, for Solomon sought to surpass all other earthly monarchs in magnificence. He had 1,400 chariots and 12,000 horsemen in his defense cities and at Jerusalem (1 Ki. 10:26-29). With at least 2 horses for each chariot and 1 each for the 12,000 horsemen, there were at least 14,800 horses in Israel's army in Solomon's day. See 1 Ki. 10:26-29, notes.