The problem with any colour is how to describe it. Genetic typing is a very recent thing so pedigrees back into the 1980s are unlikely to be helpful.
A friend has just purchased a topnotch show cob that is a silver grey with pretty dapples on his bottom. All his vet and show records describe him as “grey” but his passport ID is “black”. Changing his colour in his official ID documents is sufficiently complicated that the registry recommended we didn’t even try.
In Britain we have, for centuries, selected for “hard” colours without too much “chrome” because popular lore says they are hardier, more robust, better suited to their environment and work requirements etc - and only common-as-muck gypsy horses are broken colours. Even in gypsy cobs the majority are “tobiano” and any other coat patterns are extremely rare. They just don’t have “pinto” or “paint” colours and patterns. The advert selling a “tri-coloured tobiano” is really just selling a plain old “bay skewbald” and I really doubt anyone has tested any genetics to prove it otherwise. It is notable that horses running at the top levels of sport are still bay, chestnut, grey or black.
Over time fashion comes into play. In the 19th century greying out of a coat colour was deemed to be caused by early aging. Grey TBs almost vanished in Britain until grey French race horses started to win in the the UK. Even today some TBs make less money at auction because of an odd coat colour. Then, of course, certain coat colours are not recognised by the TB General Stud Book. Palomino only became recognised in 2007 in the UK. So look through records and you will only find “chestnut”. Anything people aren’t too certain about, based on the phenotype of the parents, when registering a foal within a few days of birth, becomes a “roan” in the TB world.
Then along come the European warmbloods and suddenly they all have long white socks because they look so snappy in dressage. When did that happen?
Meanwhile, in the States, there are so many horses with Iberian and Barb roots, from the Spanish and Portuguese conquistadors, that have different genetics from those horses of Northern Europe imported into the East Coast. These genes produce all those many, many colours and coat patterns covered by Spanish terminology that can not be easily transferred onto other breeds. These genotypes will probably not be present in modern European warmbloods except way back in their past when the Iberian horse was considered the very best warhorse and every king and general wanted one to ride so they were traded across Europe.