The scientific papers state that eurasian snakes crossed over to the americas but I don't rule out the possibility that maybe some north american snakes crossed over there and thus populated eurasia with the colubrids related to ours.
Japanese ratsnake x florida corn snake has happened in captivity and so has beauty snake x greenish ratsnake so the genetic distance between old world colubridae and new world is theoretically less that 20 million years.
To me, this means the possibility of old world lampropeltis that were possibly put under the umbrella taxon Elaphe as were many racer type snakes.
Lampropeltis getula used to be classified as Coronella getula.
Here is Coronella Girondica:

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Pituophis c. annectans
Senticolis t. intermedia
Rhinechis scalaris
Elaphe bairdi
Lampropeltis zonata
Lampropeltis t. campbelli
Lampropeltis m. thayeri