The Eastern Romance languages developed from the Proto-Romanian language, which in turn developed from the Vulgar Latin spoken in a region of the Balkans which has not yet been exactly determined, but is generally agreed to have been a region north of the Jireček Line. That there was language contact between Latin or Vulgar Latin speakers and speakers of indigenous Paleo-Balkan languages in the area is a certainty; however, it is not known which Paleo-Balkan language or languages comprise the substratal influence in the Eastern Romance languages. The substratal elements in the languages are mostly lexical items. Around 300 words are considered by many linguists to be of substratum origin. Including place-names and river-names, and most of the forms labelled as being of unknown etymology, the number of the substratum elements in Eastern Romance may surpass 500 basic roots. Linguistic research in recent years has increased the body of Eastern Romance words that may be considered indigenous. In addition to vocabulary items, some other features of Eastern Romance, such as phonological features and elements of grammar (see Balkan sprachbund) may also be from Paleo-Balkan languages. Lexical items Older Romanian etymological dictionaries tended to assume a borrowing in many cases, usually from a Slavic language or from Hungarian, but etymological analysis may show that, in many cases, the direction of borrowing was from Romanian to the neighboring languages. The current Dicționar explicativ (DEX) published by the Romanian Academy continues to list many words as borrowings, though the work of other linguists (Sorin Olteanu, Sorin Paliga, Ivan Duridanov, et al.) may indicate that a number of these are in fact indigenous, from local Indo-European languages. Though the substratum status of many Romanian words is not much disputed, their status as Dacian words is controversial, some more than others. There are no significant surviving written examples of the Dacian language, so it is difficult to verify in most cases whether a given Romanian word is actually from Dacian or not. Many linguists however favor a Dacian source for the Romanian substratum. Many of the Romanian substratum words have Albanian cognates, and if these words are in fact Dacian, it indicates that the Dacian language may have been on the same branch as Albanian. The Bulgarian Thracologist Vladimir Georgiev helped develop the theory that the Romanian language has a Daco-Moesian language as its substrate, a language that had a number of features which distinguished