you can try to contact the registry and see if they can or will give you any information.
There’s also that website allpedigree you can try. but if someone hasn’t filled in anything it won’t do you any good.
It’s hard to find any information on a horses lineage if you don’t know his/her parents.
"Take the time it takes, so that it takes less time."
"Expect a lot, accept a little, reward often."