During the 16th century, eastern Europeans stopped making krepish and instead began making filled pasta, and thus kreplach were born. This practice may have been ultimately introduced by the Tatar incursions from Asia, or Italy. This method of boiling food in water was a tremendous innovation in northern Europe since it was much cheaper than frying it in fat. The Polish version of filled pasta was called pierogi, in Ukraine they called it Varenyky, and the eastern Ashkenazi name for this pasta was the krepl or kreplekh, the plural version. At first, these dumplings could have been exactly the same, just different names in different regions all influenced from Italy or Asia
According to Claudia Roden Jews in the ghettos of Germany, through contact with their “brethren in Italy” made pasta in the 14th century, long before it reached most of Germany.  In the early 14th century, a famous Jewish scholar, Kalonymus ben Kalonyms moved from Rome to the Rhineland and was known to eat strips of boiled dough with honey (Roden, 153). While this is not nearly a dumpling, it shows that Italy and Germany had contact with each other, providing good reason to believe the kreplach originated in Germany. Later in the 14th century, stuffed pasta came to the Jews of Germany through Venice. From that point a variety of fillings were made, the most popular being the meat kreplach (Roden, 155).
This does not necessarily contradict Marks in “Encyclopedia of Jewish Food”, who claimed that the kreplach were still in its infancy during the 14th century, just a small piece of meat wrapped in a pastry and fried. While the Jews of Germany had knowledge of stuffed pasta in the 14th century, this may have not spread for another 200 years later when Europeans learned to boil food in water and create the kreplach. In fact, kreplach itself could have actually been created in the 16th century, influenced from pierogi. This is because the Yiddish word “lokshen” (noodle) comes from the Polish work “lokszyn.” Also, pasta came to Poland as a result of Italian and Asian presence in the royal courts. This could also explain why the cheese kreplach, topped with sour cream was influenced by the Turkish manti more than the Italian ravioli (Roden, 153).
In addition, during the Middle Ages, the Mishnah mentions both Spain and Italy. It is also confirmed that the Jewish foods of Italy, Greece, and France were very similar. An example of this is, vermicelli noodles became popular with the Jews of Italy and then traveled elsewhere. Jews took many cues from Italian culture, specifically making vermicelli, and tortelli. This seems very similar to the kreplach, and may be where its origins stemmed from (Deutsch, 10). In addition to this, there were also many similarities between Jewish, Italian, and French, and German foods. Therefore, taking into account the facts above, I conclude stuffed pasta itself was most likely brought from Italy to Germany, but kreplach were heavily influenced from pierogi.