One of the interesting capabilities of Solaris zones was the ability to run older versions of Solaris than that in the global zone. Marketing managed to mangle this into Containers, and it was supported for Solaris 8 and Solaris 9.
I used this extensively on one project, to lift a whole datacenter of ancient (yes, really ancient) Sun servers into zones on a couple of T5240s. Worked great.
Ah yes, Solaris. One of Larry Ellison’s many, many casualties.
Tribblix is a Solaris distribution that should feel familiar to longtime Solaris users, but with a set of modern packages on top.