How did my ancestors get there?

It seems to be that my/our ancestors had come to the so-called "South Russia" as Bessarabian Germans did. The latter in their majority had travalled from the Southwestern Germany and settled around Odessa.

 

http://www.migrazioni.altervista.org/deu/3deutsche_in_russland/2.11_auswanderung_odessa.html

It had been like that:

http://www.migrazioni.altervista.org/deu/2ostsiedlung/8.6_ostsiedlung18.html

or like that:

http://www.radiobremen.de/kultur/kino/die-andere-heimat100.html       

Other possibilities look like that:

http://www.bessarabien.de/auswanderung.php