In historical times, some ethnonyms are believed to correspond to Pre-Indo-European peoples, assumed to be the descendants of the earlier Old European cultures: the Pelasgians, Minoans, Leleges, Iberians, Nuragic people, Etruscans and Basques. Two of the three pre-Greek peoples of Sicily, the Sicans and the Elymians, may also have been pre-Indo-European. The term "pre-Indo-European" is sometimes extended to refer to Asia Minor and Central Asia, in which case the Hurrians and Urartians are sometimes included. How many Pre-Indo-European languages existed is not known. Nor is it known whether the ancient names of peoples descended from the pre-ancient population actually referred to speakers of distinct languages. Marija Gimbutas (1989), observing a unity of symbols marked especially on pots, but also on other objects, concluded that there may have been a single language spoken in Old Europe. She thought that decipherment would have to wait for the discovery of bilingual texts. The idea of a Pre-Indo-European language in the region precedes Gimbutas. It went by other names, such as "Pelasgian", "Mediterranean", or "Aegean". Apart from marks on artifacts, the main evidence concerning Pre-Indo-European language is in names: toponyms, ethnonyms, etc., and in roots in other languages believed to be derived from one or more prior languages, possibly unrelated. Reconstruction from the evidence is an accepted, though somewhat speculative, field of study. Suggestions of possible Old European languages include Urbian by Sorin Paliga, and the Vasconic substratum hypothesis of Theo Vennemann (also see Sigmund Feist's Germanic substrate hypothesis). According to Gimbutas' version of the Kurgan hypothesis, Old Europe was invaded and destroyed by horse-riding pastoral nomads from the Pontic-Caspian steppe (the "Kurgan culture") who brought with them violence, patriarchy, and Indo-European languages. More recent proponents of the Kurgan hypothesis agree that the cultures of Old Europe spoke pre-Indo-European languages but include a less dramatic transition, with a prolonged migration of Proto-Indo-European speakers after Old Europe's collapse because of other factors. Colin Renfrew's competing Anatolian hypothesis suggests that the Indo-European languages were spread across Europe by the first farmers from Anatolia.