Jamieson, Fausset and Brown on Isaiah 66:20

20. they--the Gentiles (Is 66:19).

bring ... your brethren--the Jews, back to the Holy Land (Is 49:22). It cannot mean the mere entrance of the Jews into the Christian Church; for such an entrance would be by faith, not upon "horses, litters, and mules" [Houbigant]. "Offering" is metaphorical, as in Ro 15:16.

horses--not much used by the Jews. The Gentiles are here represented as using their modes of conveyance to "bring" the Jews to Jerusalem.

chariots--as these are not found in Oriental caravans, translate, "vehicles," namely, borne, not drawn on wheels.

litters--covered sedans for the rich.

upon swift beasts--dromedaries: from Hebrew root, "to dance," from their bounding motion, often accelerated by music [Bochart]. Panniers were thrown across the dromedaries' back for poorer women [Horsley].