By historical anime series, I mean shows that portrayed important historical characters and has a storyline set during monarchial and feudal period of Japan.
Japanese language has undergone a vast transformation. The order was somewhat like:
Old Japanese -> Early Middle Japanese -> Late middle Japanese -> Early modern Japanese -> Modern Japanese
The Japanese spoken today differs from that spken during those times. I am assuming that the old Japanese is considered archaic and obsolete (just like Shakesperean English is obsolete today). So, did anime series whose story is set during those times used a different kind of Japanese? Did VAs used "archaic Japanese" for such roles or went with normal Japanese? Or did they worked with dialects*?
*FWIW, I found this piece of information:
Modern Japanese is considered to begin with the Edo period, which lasted between 1603 and 1868. Since Old Japanese, the de facto standard Japanese had been the Kansai dialect, especially that of Kyoto. However, during the Edo period, Edo (now Tokyo) developed into the largest city in Japan, and the Edo-area >dialect became standard Japanese.
So, since Kansai dialect was the standard Japanese during those times, VAs who know Kansai dialect might be suitable for such roles and story. Did historical anime used heavy dialects to give an impression of "archaic Japanese"?