Well if your referring to any Holocaust the obvious candidate might be Armenians escaping Ottoman rule for some reason in the decades prior to the Ottomans massacres of 1915/16. Or possibly on a similar theme the Asyrian Christians for some reason fleeing Mesopotamia and escaping their own massacre by the Ottomans a bit later.
There were other mass slaughters, such as of the
Dzungar by the Qing dynasty in the 18th century and as a partially nomadic group they might have had a better chance to flee. Interesting that the Dzungar who were Buddhist treated some of the groups they ruled badly including members of the Muslim Uyghurs who as a result aided in their destruction and were resettled in former's territories, where ironically they now face genocide by the Chinese.
There are probably other examples in history but those were the ones that come to mind.
In terms of the Nazis there were other groups that were persecuted by them, but other than the Jews and Roma I think most were either political groups, such as socialists and communists or other groups such as the physically or mental handicapped or homosexuals. Of course later probably many other groups would have been targeted for widespread massacres but fortunately they were defeated.