I wouldn't call them all defeated cultures.

Most of the time, cultures aren't defeated like that. They were simply rejected because they didn't serve as useful as a purpose. It's like how many religions die (excluding any that came into contact with Islam). The religions were not murdered, they were abandoned. It's the very nature of the strange: "my god is stronger" argument. These gods are not killed, they do not fight each other, but the person who says that is inadvertently arguing that their society & institutions are stronger. It may be the case in many places.

Think of how Christianity has expanded so thoroughly in Africa and the Americas. If Christianity had no value, it would not have been readily adopted by people who were getting preached at by missionaries, in the same way that you don't find Anubis compelling. People are buying into a set way of living, that must confer a benefit, otherwise they wouldn't change. They do not have to be conquered or defeated.

Again... this is intentionally excluding Islam because that's a major way of expanding itself. It's advantages are different, compared to other systems, are different. It really did defeat most of the cultures it came into contact with, barring a few.