readings. From the colonial period on there exists an extensive Mesoamerican literature written in the Latin script. Literary traditions The literature and texts created by indigenous Mesoamericans are the earliest and well known from the Americas for two primary reasons. First, the fact that native populations in Mesoamerica were the first to interact with Europeans assured the documentation and survival of literature samples in intelligible forms. Second, the long tradition of Mesoamerican writing contributed to them readily embracing the Latin script used by the Spanish and resulted in many literary works written in it during the first centuries after the Spanish conquest of Mexico. Some important literary works in Mesoamerican languages are: The mythological narrative of the Popol Vuh and the theatrical dance-drama the Rabinal Achí both written in Classical Kʼicheʼ Maya. The ethnographical work in the Florentine Codex and the songs of the Cantares Mexicanos both written in Classical Nahuatl. The prophetical and historical accounts of the books of Chilam Balam written in the Yucatec Maya language. As well as numerous smaller documents written in other indigenous languages throughout the colonial period. No true literary tradition for Mesoamerican languages of the modern period has yet emerged. Mesoamerican Linguistic Area Throughout the millennia in which speakers of different Mesoamerican languages were engaged in contact the languages began to change and show similarities with one another. This has resulted in Mesoamerica evolving into a linguistic area of diffusion, a "Sprachbund", where most languages, even though they have different origins share some important linguistic traits. The traits defining the Mesoamerican sprachbund are few but well established: the languages use relational nouns to express spatial and other relations, they have a base 20 (Vigesimal) numeral system, their syntax is never verb-final and as a consequence of this they don't use switch reference, they use a distinct pattern for expressing nominal possession and they share a number of semantic calques]. Some other traits are less defining for the area, but still prevalent such as: the presence of whistled languages, incorporation of bodypart nouns into verbs, the derivation of locatives from bodypart nouns, grammatical indication of inalienable or intimate possession. Terrence Kaufman has worked with documenting the process of this linguistic convergence and he argues that the most probable donor languages of the borrowings into other Mesoamerican languages are the Mixe–Zoquean and Totonacan languages, this supports a theory of either or both of these cultures