In the 9th century, Buddhist tradition records a contested succession, but there are many inconsistencies; contemporary Chinese histories indicate that Tibetan unity and strength were destroyed by rivalry between generals commanding the frontier armies.
In the same period, the Eastern Roman Empire had two palatine field armies (at Constantinople), three regional field armies (in the East, in Thrace, and in Illyricum) and fifteen frontier armies.
Within the frontiers the army was kept at full strength, mostly by local recruiting of legionaries and apparently of auxiliaries, too (so that Vespasian's system of having the latter serve far from their homelands gradually ceased).
On the frontier, Mr Musharraf, army chief until November 2007, still calls the shots.
Beset on their northern frontier by Soviet armies and rocket divisions, the Chinese were loath to see Vietnam unite under the tough pro-Soviet regime in Hanoi.
Personnel from the paramilitary frontier constabulary (FC), the army and police rushed to the scene while military helicopters circled overhead.
Commanders feared that if detainees were handed over to the courts and formally charged, they would be released, placing army and frontier corps troops at risk.
The TTP's reach extends across the tribal belt along the Afghan border although its capacity to strike has been impaired over the past six months following major army and frontier corps drives into South Waziristan and Bajaur.
The fighting marks the breakdown of the deal over the Swat valley early this year, whereby the Taliban were allowed to bring in their local sharia courts and system of government in return for a ceasefire and disarming of their own militias, while the Pakistan army and frontier force withdrew.
