|Type of government||Monarchy, current ruler: A Queen who lives forever|
Hersheba is a region of the Klatch continent that is sometimes mentioned but not actually featured in the chronicles. The name 'Hersheba' (a pun on 'Hershey Bar' / 'Beersheba') is something that Terry came up with in 1992 on a.f.p., when he was more or less thinking out loud about the many people who didn't get the Djelibeybi reference in Pyramids:
"[...] say Djelibeybi OUT LOUD -- I must have had twenty letters (and one or two emails) from people who didn't twig until the third time round... oh god... do they have them in the US? Should it have been called Emmenemms, or Hersheba... hmm, Hersheba... could USE that, yes, little country near Ephebe..."
The local currency is the Dong.
The country is situated on the same Rimwards coast of the Circle Sea as Klatch and is its immediate widdershins neighbour. The parallel is that of Egypt/Libya (Klatch) next door to Tunisia/Morocco (Hersheba) on the map of North Africa. On The Discworld Mapp. both countries appear to be the same size, although nothing is said about Hersheba's political significance or military strength. By default, the inference is that Klatch is the regional superpower and its neighbour exists as part of the Klatchian geopolitical orbit.
In Soul Music, we learn that Klatch and Hersheba have an uneasy relationship across a disputed border in the desert and are frequently at war with each other. The existence of the D'regs, who can and will fight anyone, is a provocation for both sides. The Klatchians consider the D'regs to be Hershebian while the Hershebians consider them to be Klatchian. With every new D'reg clash here and there, this has led to a continual simmering war along the border.
In Thief of Time, we learn of an unusual example of insect that comes from Hersheba: the Hershebian lawyer beetle.
According to The Discworld Companion, Hersheba is said to be ruled by an immortal queen. Combined with the name, this may be a reference to H. Rider Haggard's "She", the Queen of Sheba, or both. This is expanded upon in The Compleat Discworld Atlas, where it is noted that once people had given it enough time, the Queen was demonstrated not to be all that immortal after all.
Hersheba may be less powerful than it was, but it has the secret of compacting the greatest number of food calories into the smallest possible space. apparently hershebars are sought after as travellers' rations, especially if pressing on into the continent past the Cape No Return and the last coastal port at Meinem Gulf.
From Discworld Noir, we are informed (rather unreliably) that the currency of Hersheba is possibly the Hersheban groat. We are also told that the Hashishim, the first assassins, may have originated from Hersheba. Their name comes from the large amounts of hashish they ate. Being a group of insane killers feared throughout Hubward Klatch, they are both deadly and inclined to giggle, wear beads,become inconveniently peckish at irregular intervals, and grok out to interesting patterns of light and shadow on their deadly curved dagger blades. All this is, of course, debatable, since it came from a conspiracy freak in the Temple of Small Gods. The material about the Hashishim, however, is also used canonically in Sourcery.