Legibility Is Immortality

There are things that form the backbone of anglophone historical knowledge: the World Wars (particularly the Western Front), the Roman Empire, Jesus Christ, the Pyramids. The primary thing which these things share is English language legibility. Important works have been translated into or written in English and rendered into an accessible style. This alone determines whether they're remembered forever, or consigned to some dedicated historians record.

Perhaps the most often mentioned example of scorched earth is the Russians destroying their infrastructure as they retreated from the Germans. But the term's origin comes from the Second Sino-Japanese War where the defending Chinese National Revolutionary Army blew up their dams, killing half a million of their own people to successfully stall the Imperial Japanese Army on their precious Sichuan province.

Likewise, the sea invasions the Romans undertook of Britain, transporting staggering amounts of men and materiel across the sea, are far more well-known than the 3000 km naval campaign waged by the Chola Empire against the Indonesian states.

And perhaps more proximately, almost all genetic studies today use the UK Biobank in order to describe genetic relationships or detect genetic conditions. If your thing is not in there, it's unlikely to be found. If your race is poorly represented, it's unlikely you'll be as well covered. Only those who are visible and their genetic relatives are served.