The Nanzhao Tai state of South China temporarily vassalizes the Pyu center of Srikshetra in the early 800s.

Denmark is apparently united by around 800, primarily in opposition to northward expansion by the Franks under Charles I.

Contemporary Frankish annals begin in 804 to record individual kings of the Danes with whom Charles wars as his Carolingian Empire absorbs the peoples and territories to the immediate south of the Danevirke.

Harun dispatches another raid under his general Ibrahim ibn Jibril in August 804.

The Arabs cross into Asia Minor through the Cilician Gates and raid freely.

Nikephoros sets out to meet them, but is forced to return before he can do so, due to some unspecified event at his back.

On his march home, however, the Arabs launch a surprise attack at Krasos in Phrygia and defeat his army.

According to al-Tabari, the imperial army lost forty thousand seven hundred men and four thousand pack animals, while the Emperor himself was wounded three times.

The Byzantine chronicler Theophanes the Confessor confirms that the imperial army lost many men and that Nikephoros was almost killed himself; saved only by the bravery of his officers.

As Harun is preoccupied with trouble in Khorasan, the caliph now accepts tribute and made peace.

An exchange of prisoners is also arranged and takes place during the winter at the two empires' border, on the Lamos river in Cilicia; some thirty-seven hundred Muslims are exchanged for the imperial troops taken captive in the previous years.

The military commander Leo the Armenian and his comrade-in-arms Michael the Amorian had at first supported Bardanes Tourkos when he and Nikephoros I were fighting over the imperial throne in 803, but later desert him and join the cause of Nicephoros.

Leo, having distinguished himself as a general under Nikephoros, becomes strategos of the Anatolic theme.

Harun recognizes the existence of the two different politico-religious trends by assigning Iraq and the western provinces to his son Muhammad al-Amin, the heir apparent, and the eastern provinces to the second in succession, his son al-Ma'mun.

The former is the son of the Arab princess Zubaydah, a niece of al-Mansur, the second 'Abbasid caliph, and after 803 has al-Fadl ibn ar-Rabi' as tutor.

His half brother Al-Ma'mun, the elder by six months, is the son of an Iranian concubine and after 803 has as tutor a Barmakid protégé, al-Fadl ibn Sahl.

One of the founding fathers of the Hanafi school of law, Muḥammad ash-Shaibānī, chief qadi (judge) in Ar-Raqqah and a leader of the movement towards systemetizing the Sharia, dies in 804.

The final insurrection of the Angrian people occurs in 804, more than thirty years after Charles's first campaign against them.

This time, the Nordalbingians, the most unruly of the Saxon tribes, finds themselves effectively disempowered to rebel.

Charlemagne deports ten thousand of them to Neustria and gives their now vacant lands to the loyal king of the Obotrites.

Charles had wished to make Ludger Bishop of Trier in 793, but he had declined, while declaring himself willing to undertake the evangelization of the Saxons.

Charles had accepted the offer, and northwestern Saxony was thus added to Ludger's missionary field.

The monastery of St. Ludger's Abbey at Helmstedt had been founded as part of his missionary activity in this part of Germany.

To meet necessary expenses the income of the Abbey of Leuze, in the present Belgian province of Hainaut, was given him, and he was told to pick his fellow-workers from the members of that abbey.

As Mimigernaford (also Mimigardeford or Miningarvard) had been designated the center of the new district, Ludger had built a monastery there, from which the place took the name of Münster.

Here he lives with his monks according to the rule of Saint Chrodegang of Metz, which in 789 had been made obligatory in the Frankish territories.

He has also built a chapel on the left bank of the Aa in honor of the Blessed Virgin, as well as the churches of Billerbeck, Coesfeld, Hersfeld, Nottuln and others.

Near the church of Nottuln, he built a home for his sister, Saint Gerburgis, who had consecrated herself to God.

Many other women soon joined her, and so in about 803 originated the first convent in Westphalia.

Ludger founds the abbey at Werden (after an abortive attempt to establish a religious house at Wichmond on the Erft) in 799 and consecrates it in 804, on ground which Ludger himself had acquired, in fulfillment of his desire, formed since his stay at Monte Cassino, to found a Benedictine house.

The little church which Ludger has built here in honor of Saint Stephen is completed in 804 and dedicated by Ludger himself.

Kukai had taken part in a government-sponsored expedition to China in 804 in order to learn more about the Mahavairocana Sutra.

Scholars are unsure why Kukai was selected to take part in an official mission to China, given his background as a private, not state-sponsored, monk.

Theories include family connections within the Saeki-Otomo clan, or connections through fellow clergy or a member of the Fujiwara clan.

The expedition included four ships, with Kukai on the first ship, while another famous monk, Saicho was on the second ship.

During a storm, the third ship turned back, while the fourth ship was lost at sea.

Kukai's ship arrived weeks later in the province of Fujian and its passengers were initially denied entry to the port while the ship was impounded.

Kukai, being fluent in Chinese, had written a letter to the governor of the province explaining their situation.

The governor allowed the ship to dock, and the party was asked to proceed to the capital of Chang'an (present day Xi'an), the seat of power of the Tang Dynasty.

After further delays, the Tang court granted Kukai a place in the Ximingsi temple where his study of Chinese Buddhism began in earnest as well as studies of Sanskrit with the Gandharan pandit Prajna (734-810?)

who had been educated at the Indian Buddhist university at Nalanda.

In 805, Kukai finally meets Master Hui-kuo (746 – 805) the man who will initiate him into the esoteric Buddhism tradition at Chang'an's Qinglong Monastery.

Huiguo comes from an illustrious lineage of Buddhist masters, famed especially for translating Sanskrit texts into Chinese, including the Mahavairocana Sutra.

Huiguo immediately bestows upon Kukai the first level Abhisheka or esoteric initiation.

Whereas Kūkai had expected to spend twenty years studying in China, in a few short months he is to receive the final initiation, and become a master of the esoteric lineage.

Huiguo is said to have described teaching Kukai as like "pouring water from one vase into another".

Huiguo dies shortly afterwards, but not before instructing Kukai to return to Japan and spread the esoteric teachings there, assuring him that other disciples will carry on his work in China.

Meanwhile, Tang Shunzong succeeds Tang Dezong as emperor of China, but does not last until the end of the year.

Wake no Hiroyo, one of Saicho's earliest supporters in the Court, had invited Saicho to give lectures at Takaosanji along with fourteen other eminent monks.

Saicho was not the first to be invited, indicating that he was still relatively unknown in the Court, but still rising in prominence.

The success of the Takaosanji lectures, plus Saicho's association with Wake no Hiroyo, had soon caught the attention of Emperor Kanmu, who had consulted with Saicho about propagating his Buddhist teachings further, and to help bridge the traditional rivalry between the Hosso (Yogacara) and Sanron (Madhyamika) schools.

The emperor had granted a petition by Saicho to journey to China to further study Tiantai doctrine in China, and bring back more texts.

Saicho was expected to only remain in China for a short time, however.

Saicho can read Chinese language, but is unable to speak it at all, thus he is allowed to bring a trusted disciple along named Gishin, who apparently can communicate in Chinese.

Gishin will later become one of the head monks of the Tendai order after Saicho.

Saicho had been part of the four-ship diplomatic mission to Tang Dynasty China in 803.

The ships were forced to turn back due to heavy winds, where they had spent some time at Dazaifu.

During this time, Saicho had likely met Kukai, who had been sent to China on a similar mission though he was expected to stay much longer.

When the ships set sail again, two sank during a heavy storm, but Saicho's ship had arrived at the port of Ningbo, then known as Mingzhou, in northern Zhejiang Province in 804.

Shortly after arrival, permission had been granted for Saicho and his party to travel to Mount Tiantai and he had been introduced to the Seventh Patriarch of Tiantai Buddhism, named Tao-sui, who becomes his primary teacher during his time in China.

Tao-sui is instrumental in teaching Saicho about Tiantai methods of meditation, Tiantai monastic discipline and orthodox teachings.

Saicho had remained under this instruction for approximately 135 days.

Saicho spends the next several months copying various Buddhist works with the intention of bringing them back to Japan later.

While some works exist n Japan already, Saicho feels that they suffer from copyist errors or other defects, and makes fresh copies.

Once the task is completed, Saicho and his party return to Ningbo, but the ship is harbored in Fuzhou at the time, and will not return for six weeks.

During this time, Saicho goes to Yuezhou (modern-day Shaoxing) and seeks out texts and information on esoteric Buddhism.

The Tiantai school had originally only utilized "mixed" (zōmitsu) ceremonial practices, but over time, esoteric Buddhism has taken on a greater role.

By the time of Saicho, a number of Tiantai Buddhist centers offered esoteric training, and both Saicho and Gishin received initiation at a temple in Yuezhou.

However, it's unclear what transmission or transmissions(s) they received.

Some evidence suggests that Saicho did not receive the dual transmissions of the Diamond Realm and the Womb Realm.Instead, it is thought he may have only received the Diamond Realm transmission, but the evidence is not conclusive one way or the other.

Finally, on the tenth day of the fifth month of 805, Saicho and his party return to Ningbo and after compiling further bibliographies, board he ship back for Japan; they will arrive in Tsushima on the fifth day of the sixth month.

Although Saicho has only stayed in China for a total of 8 months, his return is eagerly awaited by the Court in Kyoto.