The most desirable thing that could happen at midnight, between the old and the new year, would be that the first person across the step, the first foot, would be dark-haired man bearing gifts – a piece of good black coal was considered a very acceptable offering in our part of the world.
As for being dark, that probably had to do with physical characteristics of ones own people, especially in olden times of great uncertainty, and the whereabouts of those who were out to do you no good.
A blond, blue-eyed individual standing on the doorstep might well have been a foreign invader, someone carrying weapons to do ill, rather than presenting something to brighten up the celebration fire.
Robert Burns wrote ‘Auld Lang Syne’, meaning in ‘olden times’, with something less sinister in mind, but race memory is long and not easily appeased.
I translate the title above for the benefit of the ‘sassunach’! (The Saxon)
“An’ there’s a haund, ma trusty fiere!”