Who is The Merchant from Heysen from Tevye the Dairyman and the Railroad Stories and what is their importance?

The Merchant from Heysen arranges to get a bribe to the prefect in order to get Cossack forces to stop people from out of town who are organizing a pogrom. He succeeds in protecting the local Jews, when by some miracle or scheme, the incoming train comes in as a locomotive without its cars attached.