Try this one...
In the late 2020's contact is made with an alien species. Weirdly enough the Aliens look like
US!!!
At first the UFO cranks are going "
Nordics!!!. After the cranks are calmed down and the real "
Nordics" are apologized to, the Aliens explain that they called themselves the
Tuatha. They'd been taken by aliens long ago and came back for awhile to visit their distant kinsfolk. Now the old aliens have "Passed Beyond" and they've come back, and not just the Celtic tribes. Soon all the human groups taken by the aliens will return to share their wealth and power with their long lost kinsfolk.
The world's elites are in a panic. Not every human group is represented in the stars. And some very small, poor, primitive, and oppressed people are represented by powerful extra-planetary nations. The Earth's power relationships are going to be knocked askew. Worse, most of these aliens may be technologically advanced but they are culturally and politically primitive. The Tuatha seem to get the idea of political change, or at least since they claim Ireland and those nations with large numbers of people of Irish ancestry as their kinfolk/allies, they've decided to move toward modernity. Others might refuse.
Can Earth survive our new found kinsfolk starting a primitive war with tech level twelve superscience weapons?