Japanese cuisine has a wide variety of dishes worth trying, like the lesser-known takoyaki and okonomiyaki, but the country is most known for its iconic noodles — udon, ramen, soba — and, of course, sushi. However, raw fish paired with lightly seasoned rice did not originate in Japan, but in Southeast Asia along the Mekong River.

The Mekong runs through Thailand, Vietnam, Myanmar, Laos, and Cambodia, and around the third century, citizens living along the river mostly subsisted on fish. Due to the area's hot climate, locals had to find a way to preserve food, and covered gutted and cleaned fish with a mixture of rice and salt to prevent it from rotting.

With this early method, the rice was too salty to consume and was thrown away, but eventually, the preservation practice reached Japan. Apparently being less patient, Japanese practitioners would uncover the fish after just one month after preservation, and the rice, being less salty and old, was consumed instead of thrown aside.

The next four centuries gave birth to haya-nare sushi, which Insider describes as "box-pressed cured fish over vinegar-seasoned rice," and by the Edo period in Tokyo, sushi became a fast lunch for busy workers. This period also eventually gave rise to nigiri sushi, pieces of raw or cooked fish on top of lightly compressed sushi rice.

Nigiri sushi is what many of us are familiar with today, and was first sold by the brand Hanaya Yohei; soon after, other varieties of sushi came to be. When refrigeration technology reached new heights in the 1970s, sushi's popularity and availability exploded, and the first sushi shop in the United States opened in Los Angeles in 1966.