Sassanian king Bahram V crushes an invasion…

Jangsu, the twentieth monarch of Goguryeo, the northernmost of the Three Kingdoms of Korea, has reigned from the age of nineteen reigned over the peak of Goguryeo's power, building on the territorial expansion of his father, King Gwanggaeto the Great.

Now entering his thirties, he has dedicated much of his efforts towards stabilizing a kingdom that had experienced great and sudden growth, a direct result of his father's conquests.

Jangsu has built a magnificent tomb for his father, and along with it an imposing four-meter tall tombstone carved from a single mass of granite and engraved with his father's accomplishments (now known as the Gwanggaeto Stele).

Of such imposing dimensions is the tomb and its grounds that it requires three hundred and thirty people to tend it at all times, called from different regions and tribal backgrounds to guard and clean the tomb in perpetuity: a demonstration of the effective consolidation of the Goguryeo kingdom and monarch's power at the time of Jangsu's succession.

In 427, he transfers the Goguryeo capital to from Guknaesong (modern Ji'an on the Sino-Korean border) to …

…P'yonggang (Pyongyang).

Many modern Chinese historians argue that since the early Goguryeo capital had been located in what is now China, the history of that kingdom prior to 427 should be regarded as Chinese history).

There are various reasons for this shift: to prepare for the offensive against Baekje and Silla in the south and to create a greater and more magnificent capital befitting a kingdom that has experienced large-scale expansion.

After moving the capital southward, King Jangsu decides to continue the conquests of his father.

Helian Chang sends his brother Helian Ding south in spring 427 to try to recapture Chang'an, but Helian Ding's forces become stalemated with Daxi's.

In response, …

…Emperor Taiwu makes another attack on Tongwan.

Helian Chang initially takes Helian Ding's suggestion to try to defend Tongwan until he can defeat Daxi, but misinformation that Helian Chang receives then induces him to come out of Tongwan to engage Northern Wei forces.

Emperor Taiwu defeats him in battle, causing him to be unable to return to Tongwan and forcing him to flee to Shanggui (in modern Tianshui, Gansu), allowing Emperor Taiwu to capture Tongwan.

In the first of what is to be a string of marriages that could be characterized as either political or self-aggrandizing, he takes three of Helian Bobo's daughters as his concubines.

Upon hearing of Tongwan's fall, Helian Ding disengages from Daxi and joins Helian Chang at Shanggui as well.

Pannonia Prima is assimilated into the Huns’ territory by 427.

Rome will never regain control of this area, but it will remain a Roman province until the fall of the Ostrogothic Kingdom in 553.

Rabbi Ashi of Babylon, the primary editor of the Babylonian Talmud, revives the Sura rabbinical academy and heads it for more than fifty years while gathering material for his work.

He dies in 427.

Aetius arrives with an army of roughly forty thousand in southern Gaul in 427 to find Arelate, an important city in Septimania near the mouth of the Rhone, under siege from the Visigoths led by their king Theodoric I. Aetius defeats Theodoric, lifts the siege, and drives the Visigoths back to their holdings in Aquitania.

Daxi and Qiudun Dui, in trying to capture Helian Chang in 428, instead become trapped by Helian Chang in the city of Anding (in modern Pingliang, Gansu).

However, Daxi's subordinates Weichi Juan and Anchi Jia make a surprise attack and capture Helian Chang.

Helian Ding ssumes the imperial throne of Xia.

Meanwhile, Emperor Taiwu treats Helian Chang as an honored guest, supplying Helian Chang with the same supplies that he himself uses, and he marries his sister Princess Shiping to Helian Chang and creates him the Duke of Kuaiji; he also greatly rewards Weichi and Anchi and creates them dukes.

Daxi, humiliated that his subordinates had captured Helian Chang and he himself appears helpless, aggressively pursues Helian Ding, but instead is defeated and captured by him.

In fear, Qiudun and Tuoba Li, the Prince of Gaoliang, abandon Chang'an as well and flee to Puban, allowing Xia to recapture Chang'an.