Throughout its prehistory and early history, the region and its vicinity in the Yangtze region was the cradle of unique local civilizations which can be dated back to at least the 15th century BC and coinciding with the later years of the Shang and Zhou dynasties in North China. Sichuan was referred to in ancient Chinese sources as Ba-Shu (巴蜀), an abbreviation of the kingdoms of Ba and Shu which existed within the Sichuan Basin. Ba included Chongqing and the land in eastern Sichuan along the Yangtze and some tributary streams, while Shu included today's Chengdu, its surrounding plain and adjacent territories in western Sichuan. 

The existence of the early state of Shu was poorly recorded in the main historical records of China. It was, however, referred to in the Book of Documents as an ally of the Zhou. Accounts of Shu exist mainly as a mixture of mythological stories and historical legends recorded in local annals such as the Chronicles of Huayang compiled in the Jin dynasty (265–420), with folk stories such as that of Emperor Duyu (杜宇) who taught the people agriculture and transformed himself into a cuckoo after his death. The existence of a highly developed civilization with an independent bronze industry in Sichuan eventually came to light with an archaeological discovery in 1986 at a small village named Sanxingdui in Guanghan, Sichuan. This site, believed to be an ancient city of Shu, was initially discovered by a local farmer in 1929 who found jade and stone artefacts. Excavations by archaeologists in the area yielded few significant finds until 1986 when two major sacrificial pits were found with spectacular bronze items as well as artefacts in jade, gold, earthenware, and stone. This and other discoveries in Sichuan contest the conventional historiography that the local culture and technology of Sichuan were undeveloped in comparison to the technologically and culturally "advanced" Yellow River valley of north-central China. The name Shu continues to be used to refer to Sichuan in subsequent periods in Chinese history up to the present day.
what wasn't well documented?
is it referred to anywhere?
where?
how is it seen?
where was the cradle of the world?
beginning?
who was ruling then?
where?
what is discusses in very old documents?
what was one source called?
The existence of the early state of Shu
The existence of the early state of Shu was poorly recorded in the main historical records of China.
yes
 referred to in the Book of Documents as an
in the Book of Documents
referred to in the Book of Documents
as an ally of the Zhou
o in the Book of Documents as an ally of the Zhou
the Yangtze region
 the region and its vicinity in the Yangtze region was the cradle of unique local civilizations which can be dated back to at least the 15th century BC a
at least the 15th century BC
Yangtze region was the cradle of unique local civilizations which can be dated back to at least the 15th century BC
the Shang and Zhou dynasties
coinciding with the later years of the Shang and Zhou dynasties in North China.
in North Chin
f the Shang and Zhou dynasties in North Chin
Accounts of Shu
Accounts of Shu
the Chronicles of Huayang
 Accounts of Shu exist mainly as a mixture of mythological stories and historical legends recorded in local annals such as the Chronicles of Huayang 