Who doesn't love a nice stack of potato latkes for Hanukkah? Tradition, right? But as I was frying up my seasonal potato pancakes, I started thinking... potatoes didn't exist in the Old World until 1492. So what were Jews using to make לביבות before Christopher Columbus? I see a few recipes for zucchini latkes, so is that it?
Cheese. Something along the lines of Ricotta or Farmer cheese.
In the days of the Assyrian conquest, the general Holofernes was stopped by a woman named Yehudis. She invited the enemy general into her tent, fed him warm milk and salty cheese, and after the cheese made him thirsty -- wine. When the alcohol from the wine and the lactase from the warm dairy put him to sleep, she beheaded him. The Judeans went on the attack while the army was leaderless, and drove off the Assyrians.
This story is both in our tradition and recorded in the Apocrypha, in the Book of Judith. It happened centuries before Chanukah. But in the Middle Ages, Chanukah was thought of in broader terms, also including a number of related events when Judea was a vassal state and we fought off the tyrannical empire.
So, to celebrate Hashem's "Hand" in driving off Holofernes, dairy products became a staple of Chanukah food. Including cheese latkes, first documented in the 14th century.
From there, people who wanted their latkes with meat meals used root vegetables. Turnip latkes. And then, when the potato arrived, they took over.
(Encyc. of Jewish Food by Gil Marks, Houghton Mifflin Harcourt 2010. Pg. 707. More sources about cheese latkes in Harel13's answer to a question about Chanukah jelly donuts, here.)
Cheese latkes are still a thing, though. My mother's are a big part of my children's and grandchildren's Chanukah memories.