It isn't "far smaller" than Qing nor is it "slightly larger" than Han and Ming, its over twice of Ming's size.
North:
In the fourth year of Zhen Guan(630) after the Tang destroyed the Eastern Tu Jue empire, all tribes south of the Gobi up to the old Turkish capital of Otugen was subjugated. Mongolia was zoned into Youzhou in the east and Lingzhou in the west and into four Dudu and six Zhou, from which left-terrtiory incorporated into Dingxiang and right-territory to Yunzhong Dudu Fu. Those north of the Gobi belonged to the tiele confederation led by the Xue Yan Tuo tribes although they submitted to the Tang as early as as the 2nd year of Zhen Guan (627) they were independent. In the 20th year of Zhen Guan (646), the Xue Yan Tuo invaded Tang territory taking advantage of the Korean campaign with a recorded number of 200,000 troops. The north was lightly defended, but never the less, the Xue Yang Tuo was crushed by Li Shi Qi's border army consisting of 60,000 Tang troop and 5000 TuJue auxiliaries. The Xue Yan Tuo retreated north but faced a blizzard that took away 9/10 of their troops, following this disaster the Uighur rebelled, and asked for Tang aid. In the following year, the Tang army crossed the Gobi and joined the Uighurs and overthrew the Xue Yan Tuo. The north of the Gobi up to Lake baikal now became part of the Tang territory as well. In that year Tai Zong set up the An Bei (pacified north) Du Hu Fu (protectorate) north of the Gobi and rezoned the Tie Le (including Uighurs) into 6 Du du fu and 7 prefectures. Later that year, he set up the Yen Lang Du Hu Fu (protectorate) up to the Angara river north west of Lake Baikal, (in 663 it will be moved back into Uighur territory) this marks the furthest northern extent of Tang. In 663, the Chang Yu Du Hu Fu is set up for the tribes south of Gobi. In 679, Chang Yu protectorate would rebel but crushed. Yet in 682, the Tu Jue rebels in north of the Gobi and Tang withdrew from An Bei, Chan Yu and the An Bei (Pacified North) protectorate became one and would remain until the end of Wu Zhao's reign.
West:
In the west, the Western Tujue during the reign of She Gui Kaghan, their territory streched from Jade gate in the east to the Aral sea in the west, while the south covered present day northern Afghanistan. In the 14th year of Zheng guan (640) Tang occupied the kingdom of Gao Cang(present day Turfan)and created the An Xi(pacified west) protectorate. Slowly, it occupied, the rest of the Tarim and tribes of the Western Tujue, in 658 the rest of the Tujue khanate was occupied. The whole of the western Tujue khanate was zoned into protectorates. From Tien Mountain to the Aral Sea, the territory is zoned into Kung ling and Meng Chi protectorate and subdivided into over a dozen Du du fu and zhou. All these protectorate are under the supervision of the protector general of the An Xi protectorate. In 661, Tang further zoned the territories south of the Oxus and the 16 kingdoms of the tarim basin reaching the border of Persia. This was the height of Tang's eastern expansion. One of the protectorate of the Pacified West was ruled by the last prince of Persia, Peroz who escaped in 651 for the Tang after the arabs destroyed the Sassanid empire. He will keep on fighting the Arabs until the 670s when he is again forced to leave by invading arabs and go back to China. While in 665, the western turkish tribes rebelled and in 670, Tubo(tibet) attacked the Tarim and Tang retreated back to Turfan, but the protectorate of Kung ling and Meng Chi was still loyal to Tang until forced by arabs and later Tujue to abandon their territory.
Here is a list of major Tang protectorates of the west:
In Chinese history the territories of present Day Russian Turkestan were called Nine kingdoms of Zhao Wu.
These nine kingdoms are Samarqand, Boukhara,
Kesh, Khebud,¨Koshana
Maimargh, Khwaresm, Betik.
1. Tashkent. Also known as Shi Guo 石国 (rock kingdom) in Chinese was made into the Da Wan prefecture (du du fu) in 658 A.D.
2. Samarkand, called Kang Guo 康国 was made into Kang Ju Du Du Fu
3. Maimargh, known as Mi Guo 米国, or rice kingdom was made into Li Nan prefecture
4. Koshana, known as He Guo 何国 was made into Xiang Zhou in 641 A.D.
5. Bukhara also known as An Guo 安国 was made into An Xi Zhou
In addition, beyond the nine kingdoms of Zhao Wu there was
1. Zhi Ba Zhou prefecture in present day in Tajikistan.
2. Tien Ma Du Du Fu also in Tajikistan.
3. Ban Zhou Du Du Fu in Uzbekistan
4. Gao Fu Zhou Du du Fu also known as Ferghana.
5. Wang Tin Zhou prefecture southwest Tajikistan
6. Gu Mo Du prefecture in Uzbekistan
7. Yue Zhi prefecture in Northern Afghanistan
8. Da Han(great Khan) prefecture
9. Qi Sha Zhou prefecture in northwestern Afghanistan
10. Xiu Xian prefecture in present day Kabul, capital of Afghanistan.
11. Xie Feng prefecture in central Afghanistan
12. Tiao Zhi prefecture, southern Afghanistan
13. BoSi (Persia) prefecture, its not in Iran but in Turkmenistan, because the Sassanian kingdom is destroyed by the Arabs, the last prince, Peroz escaped to Tang and was enfeoffed this territory as king of the new Sassanid Persia. Although this kingdom was abandoned in the 674 from new arab agrression. Tang army escorted Peroz back in 679 a.d.
East:
In the North East, in 627, Kitan of Manchuria submit to Tang, and in 648, Tang set created Song Mo protectorate over the kitans. While created the Yao Le protectorate over the Xi tribes. In 692, Tang also created the Wei Shi protectorate over the Wei Shi nomads in Northern Manchuria.
All of them was under the supervision of the An Dong(Pacified East). In 660 Tang destroys kingdom of Paikche and in 668 destroys Koguryo, set up Gao Li protectorate and BoHai prefecture. These would become independent in 698 and Kitans will rebel in 696 but resubmit to Tang in 714 and rezoned their teritory to Tang protectorate. While BoHai would be again made into Tang prefecture in 713 A.D. Further west, the Tagn created the Black water Mohe prefecture on the Amur river right after setting up prefecture over BoHai.
South:
Tang's empire in the South is the smallest, but in 679 Tang set up An Nan (Pacified South over Yunnan and Vietnam.) In Yunnan, Tang defeated the Zheng river tribes and the 6 Zhao was zoned into numerous prefectures. In 618 A.D. Tang defeated the Xie Long Yu, chieftain of the Zang Ke Man 2 years later he was made the governor of the Zang Zhou, in A.D.629 Xie Yuan Shen of the Dong Xie Man was made into Ying Zhou. In the same year Chief Zhao Mo of Nan Zhao Man yielded his allegience and was made into Ming Zhou. In 737 the kingdom of NanZhao united the other six Zhao under Tang supervision and support and hence Yunnan became the Nan Zhao kingdom which remained subjected to Tang until 750 A.D.
During its height Tang had over 800 small Zhou prefectures and 1500 Jun within the empire itself.
A span of territory that streched from Manchuria to the Aral Sea and Siberia to Central Vietnam.
The map is already posted in another thread of the extent of the Tang.
http://www.nhyz.org/...n/asia7cen2.jpg
While Tang's political sphere is even further afield than any other dynasty.
http://vip.6to23.com...ity8/map/16.jpg
And so to rest