The medieval Dalmatia had still included much of the hinterland covered by the old Roman province of Dalmatia. However, the toponym of "Dalmatia" started to shift more towards including only the coastal, Adriatic areas, rather than the mountains inland. By the 15th century, the word "Herzegovina" would be introduced, marking the shrink of the borders of Dalmatia to the narrow littoral area where was spoken the Dalmatian language (that was being assimilated into the venetian language).