In German, it’s called “meerrettich” (sea radish) because it grows by the sea. Many believe the English mispronounced the German word “meer” and began calling it “mareradish.” Eventually it became known as horseradish. The word “horse” (as applied in “horseradish”) is believed to denote large size and coarseness.
Marco Polo (1254-1324) was an Italian voyager and merchant who was one of the first Europeans to travel across Asia through China, visiting the Kublai Khan in Beijing. He left in 1271 (he was a teenager at the time) with his father (Nicolo Polo) and uncle (Maffeo Polo); they spent about 24 years traveling.