We had a "close" flyby (0.82 lightyears) about 70,000 years ago!

https://en.wikipedia.org/wiki/Scholz%27s_Star

> A star is expected to pass through the Oort Cloud every 100,000 years or so.[4] An approach as close or closer than 52,000 AU is expected to occur about every 9 million years.[2] In about 1.4 million years, Gliese 710 will pass somewhere between 8,800 and 13,700 AU from the Sun.

Just wow.

Maybe interstellar travel is basically impossible but there might be very long lived civilizations that propagate to others stars when one comes near by. Imagine what happens when both stars are populated by different long lived civilizations and they start to get near each other. I would love to read a good book speculating about such an event.

That "close" encounter was still over three orders of magnitude further out than Pluto (which has a distance of around 0.000624 ly).