Above (5:6), it says that he had 40,000 stables. Here it says that he added chariots and horsemen, and he had [only] 1,400 chariots and 12,000 horsemen! And in Divrei ha'Yamim, first it says that he had 1,400 chariots and 12,000 horsemen (1:14), and afterwards, 4,000 stables and 12,000 horsemen (9:25)!
Refer to 5:6:4:1-2 and the notes there.
How many chariots were in Arei ha'Rechev, and how many were in Yerushalayim?
Rashi, Mahari Kara: In Arei ha'Rechev he had 1,400, and 300 in Yerushalayim. This is why Divrei ha'Yamim II, 1:14 says that he had 1,700 1 .
Some old texts of Divrei ha'Yamim say so; recent texts say 1,400. (PF)
What is the meaning of "va'Yanchem"?
Rashi: He conducted them. Radak - it is Hifil, like "Hinchani b'Derech Emes" (Bereishis 24:48). In Divrei ha'Yamim II, 9:25 it says va'Yanichem, from the root Heni'ach (he left).
Radak citing Targum Yonasan: He caused them to stay.
Radak: After gathering them in Yerushalayim, he stationed them in Arei ha'Rechev, and kept some in Yerushalayim.
What are "Arei ha'Rechev"?
Radak: It is where he stationed chariots and horses. 'Rashi' (Divrei ha'Yamim 1 14) - they are called so because the king's Rochevim (riders) are there.
Radak (Divrei ha'Yamim 1 14): It is where they raised horses.
Why does it mention here how many chariots and horsemen he had?
Malbim: In addition to serving Shlomo amidst love due to his Chachmah, kings served him amidst fear, for he had many horses, chariots and horsemen ready for war.
