There was slavery in the nations of the UAE before the UAE was formed, namely: Dubai, Abu Dhabi, Sharjah, Ajman, Umm Al Quwain, Fujairah, and Ras Al Khaimah.
It’s also worth noting (this discussion is brought up every year) that the Emancipation Proclamation was not nearly as monumental as some think, as it freed *southern* slaves, not northern ones. It also did it at a time where the south was the Confederacy, so arguably Lincoln didn’t have the authority to free their slaves anyway. It did however somewhat lay the groundwork for slaves being freed later on.