This chapter1 is about the historical development of Tsakonian and the unique aspects of its current situation. Tsakonian is one of the most mysteriousModern Greek dialects that is generally considered to be a direct descendant of Ancient Greek Doric Laconian which developed in separation and isolation. It has a number of rare features that can scarcely be explained from the point of view of Greek dialectology and historical grammar. These involve phonetics (such as (/ʒ/ or /ʃ/ < /ri/ or /nd/ < /z/) and morphosyntax (e. g., absence of a synthetic present and imperfect, and special regulations in the placement of pronominal clitics). Such features cannot be found elsewhere in Modern Greek dialects. Linguistic descriptions of Tsakonian are almost always accompanied with the statement that Tsakonian is the only (sic!) Modern Greek dialect which does not originate from the Hellenistic Koiné. But it is not clear how that fact, even if true, would explain the “strange” features of Tsakonian as their connection with Ancient Laconian are still to be demonstrated. A logical explanation would be interaction with other languages during the Byzantine and Post-Byzantine periods since toponymic and lexical data suggest that Greeks were not the only residents of the region. Still the possibilities for reconstructing any details are very limited. Unlike previous studies, this chapter demonstrates that Tsakonian in its evolution was not entirely independent of the influence of other languages and dialects. At least during the last two centuries Tsakonian had constant contact only with Standard Modern Greek. The study of earlier stages of Tsakonian demands that the researcher hypothesize some past contact situation but not to be content just with a pure description of the contemporary state of the art. While presenting the rare and amazing interplay of archaisms and innovations that make Tsakonian what it is, the goal of this paper is somewhat challenging. On one hand, I intend to discuss the limits and possibilities of reconstructing past contact and, on the other hand, to show why the contact-oriented approach may be important for Tsakonian studies. This chapter is mostly based on data collected by the author between 2010 and 2019 in Tsakonian-speaking villages of Peloponnese (Greece).