You might be interested in the history of the Assyrian Church of the East. While (obviously) not as old as Judaism, it was wildly different from either the Orthodox or Roman Catholic tradition in doctrine, while still being able to claim apostolic roots. Specifically, the Church followed Nestorian doctrine of Christology, which had been condemned at the Council of Ephesus in 431. My understanding of theology in this area is weak, but the basic gist is that the Western churches held that Christ contain one incarnate nature of the Word (fully divine and fully human at once), Nestorius held that Christ contained two full, but dis-unified natures.

The reason why this community is interesting, in regards to your question, is that is was based in the Sasanid Empire in the Middle East and for many centuries it had almost no contact with the West. It had to compete and/or co-exist with sometimes hostile majority religions, such as Islam, but was able to spread over Asia. Around the 10th century, it had the biggest geographical extent of any of the branches of Christianity. It established communities in India (also known as St. Thomas Christians) which exist to this day as well as others in China and among the Mongols. Other communities still exist in Iran, Iraq and Syria and currently one branch called the Chaldean Catholic Church regularly interfaces with the Roman Catholic Pope.

References:

I've read two books on this. One is called The Lost History of Christianity: The Thousand Year Golden Age of the Church in the Middle East by Philip Jenkins (2009). The Other is The Church of the East: An Illustrated History of Assyrian Christianity by Christoph Baumer (2006).

Full disclosure, I am a layperson on this topic and would appreciate anyone correcting my points, especially differentiating Nestorian Christianity from other churches.

There is evidence to suggest that Australian Aboriginals have passed on oral accounts of the sea levels rising since the end of the last Ice Age.

The article linked above suggests these stories could be in the region of 10,000 years old, and Aboriginal culture in general is accepted as being at least 40,000 years old.

Not sure if this is quite what you're asking since Australia spent most of those 40,000 years isolated from the rest of the world, but there were hundreds of tribes that were pretty good at maintaining their identity and culture until Colonisation.

Is there any hard scientific evidence linking modern day Jews to the Hebrews of the bible?

Are the ancient Chinese "the same" as the modern Chinese? The ancient Indians? The ancient Egyptians? In each case, there are important differences that are obscured by our use of the same name for peoples across thousands of years. For instance, it is difficult to talk about ancient Indians (or modern Indians for that matter) as an ethnic group and not just the people inhabiting the geographical area called India. Similarly, English usage doesn't really distinguish between ethnic Han Chinese (who did not necessarily use a single name throughout their long history) and the inhabitants of China.

The Jews have a better claim to being a single group, but still Jewish culture (customs, religious practices, language) would have varied widely throughout history and regions. What stayed the same was the label and shared sense of identity, which for most of history was based on Judaism.

Anyway, if you are looking for ethnic labels still in use today that have a history of thousands of years, there are numerous examples such as Persians, Nubians, Assyrians, and Armenians as well as the Samaritans (although rabbinic Judaism considers them a branch of Jews). How much continuity there is between ancient bearers of these labels and the modern counterparts may be disputed, of course.

The Romani are a prime example of an ethnic group spread throughout a vast area and not concentrated in a "homeland". You can also find other groups like the Circassians and Assyrians who are found mostly outside their historical homeland.