They'll call them aliens, but I'm pretty sure us humans have a common ancestor with them.

Probably full of 1990's technology, but discovered in 1910. Why did we suddenly gain interest in Antarctica in 1910? Because in 1900 we started putting radios aboard ships. Passing into the antarctic circle, someone noticed a signal. We arrived and opened the Sarcophagus, Pandora's Box. We (today's elites) found the hidden technologies and reintroduced them in a slow drip back to humanity.