State of Xu 徐 Unknown–512 BC

Bit of a long shot, but would anyone ​​​​​know where I could source coins from
the State of Xu. It is the only letter of the alphabet missing from my collection.

Also do any other countries or regions begin with the letter x?

Kind regards in advance

From the Every Country list:

China:
Xia Dynasty, 2000–1500 BC
Xin Dynasty, Wang Mang interregnum, 7–23 AD
Xia Kingdom, 407–431
Tartar Dynasties:
Xi Liao (Western Liao, Qara Khitay state), 1124–1218
Western Xia (Xi Xia) Dynasty, 1032–1227

And then there's Sinkiang (Xinjiang)

Mexico:
Xalapa (Jalapa), Veracruz, 1824, 1836, ND, denomination uncertain (scarce)
Xoloc (Xolalco), Mexico, D.F., 1810, denomination uncertain (very rare)

https://groups.io/g/Everycountry/

Thanks for the information, I also found this on numista.

https://en.numista.com/catalogue/pieces186076.html

Xanadu