unified

Emperor Yang of Sui was planning "Koguryo" subjugation of the Korean Peninsula. (高句麗)
After all，this became the fatal wound of Sui.
At that time，people of Sui was suffering from serious poverty already.　

612AD，Sui ran the attack, but it failed due to counterattack of the Koguryo.
But emperor Yang did not give up Koguryo conquest.
He organized a new expeditionary force immediately.

But during this period, rebellion by warlord of Sui occurred.
Taking this opportunity, rebellion occurred in various locations.
　
619AD，the Sui dynasty vanished eventually.
And the Tang dynasty was born.


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Koguryo was repulsed Sui.　
But they were also battered by it.

There was a country called "Silla" in the south-east of the Korean Peninsula. (新羅)
By contrast，they raised the national strength gradually.
　
And there was a country called "Baekje" in the southwest of the Korean Peninsula. (百済)
As a corollary，they began to receive pressure of Silla.　　

Baekje tried to restrain Silla in conjunction with Koguryo and Japan.


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But at that time，king named "Muyeol" was present in the Silla. (武烈王)
He went to Tang and Japan himself.
(At this time，he was before the throne yet.)
　
He established an alliance with Tang.
And he succeeded to suppressing of the anti-Silla forces of Japan.
　
System of public administration of China at that time would have been the highest level in the world probably.
He introduced to Silla it.　
He succeeded in establishing a "modern" national system.
　
660AD，allies of the Silla and Tang destroyed Baekje.　
Immediately after this，Muyeol died.
　
But then Silla destroyed Koguryo.
And they were excluded forces of Tang from the Korean Peninsula.
　
This Silla became a unified dynasty of Korea first.