The Azuma Kagami, the official chronicle of the Kamakura shogunate, records that Yoritomo selected Kamakura specifically for its defensive terrain. The chronicle refers to the passes simply as "-zaka" -- slopes -- listing them as Kobukurozaka, Daibutsuzaka, Gokurakuzaka, and others. The term "Seven Entrances" (Nana-guchi) appears later, in Muromachi-period literature around 1450, by which time the passes had already acquired legendary status. Each one was a declared historical landmark, and together they formed a ring of controlled access points that turned a small coastal city into one of the most defensible positions in medieval Japan. Fortification remains -- artificial cliffs and leveled fighting platforms -- are still visible along several of the passes today.

In 1240, the Kamakura shogunate ordered improvements to the pass connecting the capital to the port of Mutsuura, a critical hub for salt production and maritime trade with provinces like Awa, Kazusa, and Shimosa, as well as Korea and China. Construction began the following April, and Hojo Yasutoki, the shikken (regent) himself, personally directed the work -- carrying stones and dirt on horseback to speed the project. The resulting Asaina Pass became the steepest of the seven entrances, a lung-burning climb that rewarded defenders with commanding views of any approaching force. On both sides, the remains of fortifications are still visible: artificial cliff faces carved to deny footholds, and flat terraces where soldiers could mass for counterattack. Near the Kamakura side, a stone stele stands beside Saburo Falls, commemorating the pass's designation as a historical landmark in 1969.

The passes were not merely theoretical defenses. They were tested in battle. The most dramatic test came in 1333, when Nitta Yoshisada led a massive assault on Kamakura to overthrow the Hojo regency. His forces attacked along multiple passes simultaneously. At the Gokuraku Pass -- a road opened by the priest Ninsho, founder of Gokuraku-ji temple, who had flattened a hillside to create it -- generals Odate Muneuji and Eda Yukiyoshi pushed their troops forward and clashed with Kamakura's defenders under Osaragi Sadanao. At the Kewaizaka Pass, fighting raged across a slope whose very name carries the violence of its history: one theory holds that the name derives from an incident in which makeup was applied to the severed head of a captured Taira clan shogun to make identification easier. Nitta's invasion ultimately succeeded, but only after his forces found a way around the passes entirely, wading through the shallows at low tide along the coast.

Several of the seven passes survive in recognizable form. The Daibutsu Pass, running from above the modern Daibutsu Tunnel through Kajiwara and Yamazaki to link Kamakura with Fujisawa, was repaired repeatedly from the Edo period through the Meiji era and is now a designated Historic Site. The Kobukurozaka Pass, first recorded in the Azuma Kagami in 1235, follows an old road built by the Hojo regents from Tsurugaoka Hachimangu toward Yamanouchi and Kencho-ji. The Kamegayatsu Pass, whose name appears in the chronicle as early as 1180, connected the area near modern Kamakura Station to the temples of Kita-Kamakura. Some have been paved over. Others remain rough footpaths through bamboo and cedar groves. The Shakado Pass, though not counted among the seven because it connected two areas within Kamakura rather than leading outside the city, is now closed entirely due to rockfall danger -- a reminder that the same geological forces that made these passes defensible also make them unstable.