Gainan (溉楠) is the former capital of the Nemuland and of the Yonggan State as a whole under the Nara khaganate.

Although Gainan is an ancient city of great spiritual significance to the Yonggan, and the Nara and Ikulu clans in particular, it was a small mountain town for many centuries. During these years, it was noted mainly for an important shrine, where an exceptionally stately grove of Yonggan Redwood grew at the site of a mineral spring pool.

It was reconstructed as Gainan Palace City was built during the early years of the Ri Dynasty; the official refounding as Gainan Palace City was by the first Imperial Prince of Jin Nara Aisin (納喇·愛新), toward the end of the Nara-Hao wars. It was substantially completed early in the reign of the Renxian Emperor (r. 745-712 BG). The city consists of a palace complex, inner fortified city, and an outer zone with secondary defenses - somewhat similar to Ba Sing Se, but on a far smaller scale and with nothing particularly equivalent to the agricultural zone. The Ri-era palace was built at a cost of 220,000 silver taels from the feudal revenues of the Imperial Prince of Jin.

The last major addition to the palace itself was the Hall of Solar Radiance (日光輝殿), built for the Muri emperor, (born Prince Taiku), whom the incumbent Yonggan khagan attempted to install as a successor to Qin the Great. When the Hao Ting conquered Gainan, they turned the Hall of Solar Radiance into a marketplace, carrying off its ornamentation as spoils of war. The other palace buildings were similarly stripped and auctioned off, as the Hao Ting felt that grand civic buildings and fortifications might tempt future vassal rulers or ambitious governors. Ultimately, they moved the administrative capital away from Gainan Palace City altogether, feeling that the city was too devastated to be suitable. Instead, the capital of the directly-ruled Yonggan state was moved to Garunggu, on the eastern border of the country.

Today, the city has recovered from its sack and is a significant settlement and commercial center for Yongganguo. However, its greatest significance, in the eyes of many Yonggan today, is spiritual. Since the Yonggan Nationalist regime came to power at the expense of the appointed governor from Ba Sing Se, the khagan has regularly visited Gainan on his circuit of major cities. His palace there remains comparatively modest, since the grand public buildings were long ago appropriated for other uses, but there is some talk of restoring the Hall of Solar Radiance for his use.