Departing to Bulgaria by train from Moscow, you travel through the territory of Ukraine and Romania. Russians do not need a visa to enter Ukraine (you need either a Russian or a foreign passport), and for a transit through Romania you only need to have a valid Bulgarian visa. At the time of entry into the territory of Romania, the Bulgarian visa must already be in effect.

Moreover, visa-free transit through the territory of Romania is allowed with a residence permit, either valid short-term or long-term visas to Bulgaria or Cyprus, all types of visas or residence permits in the Schengen countries, or residence in Liechtenstein.

The maximum period of stay in Romania for a transit visa is 5 days for each entry and only within the validity period of the above visas.