Now one would argue that many ethnic groups have experienced slavery in history, and they would be correct. However, in 28:68 two distinctions are made that sets this event apart from them all. The first distinction scripture points out is that Israel will go back to Egypt (or Slavery) again for a second time, here it establishes that Israel were slaves in very oppressing and terrible conditions once and will return there again. The second distinction and most important, is that the second and last time they went back to Egypt or slavery, it would be on ships. And with that said, there is only one people, not race, and one event in history that fit this specific prophecy.