The "slaves" of Deuteronomy 21:10-14 were not of "Hebrew origin". They were slaves belong to the Israelis that were captured in war.
Deuteronomy 21:10–14
10 When you go out to war against your enemies, and the Lord your God hands them over to you and you take them captive, 11 suppose you see among the captives a beautiful woman whom you desire and want to marry, 12 and so you bring her home to your house: she shall shave her head, pare her nails, 13 discard her captive’s garb, and shall remain in your house a full month, mourning for her father and mother; after that you may go in to her and be her husband, and she shall be your wife. 14 But if you are not satisfied with her, you shall let her go free and not sell her for money. You must not treat her as a slave, since you have dishonored her.
Incomplete. Yes there were foreign slaves captured in war, but also Hebrews could buy and sell foreign slaves in the market not only in their own markets, but in other kingdoms. Hebrew women may also be bought and sold in the slave market. Yes, Hebrews had slave markets.