Here you go:
“Most likely, the Beta Israel arrived in Ethiopia between the first and sixth centuries, coming as merchants or artisans from various countries in the region.“
A history of the Beta Israel, the Jews of Ethiopia.
www.myjewishlearning.com
The community started a good 100 to 600 years too late for Joseph or Mary to have come from Ethiopia.
If you prefer genetic analysis, it was mid first millenium:
Many historians are convinced that Ethiopian Jews are medieval converts from Christianity. But mounting genetic evidence, and new scholarly research, suggests the Jewish origins of the Beta Israel, who today live mostly in Israel, pre-dates Ashkenazi European Jewry.
geneticliteracyproject.org
Either way, in 30 BCE there was no Sudanese or Ethiopian Jewish community for Joseph and Mary to have come from.
The whole theory comes from racist pseudo-scholars in AA studies departments.