As a strategical centre Jalalabad is one of the most important positions in Afghanistan, for it dominates the entrances to the Laghman and the Kunar valleys; commanding routes to Chitral or India north of the Khyber, as well as the Kabul-Peshawar road.
From Kabul the old route followed the Kabul river through the valley of Laghman (or Lamghan, as the Afghans call it) over a gentle water-parting into the Kunar valley, leaving Ningrahar and Jalalabad to the south.
At Jalalabad the winter and the climate generally assume an Indian character.
The province of Jalalabad is about 80 m.
Between Kabul and Jalalabad there are two roads, one by the Lataband pass, and the other and more difficult by the Khurd-Kabul and Jagdalak passes, the latter being the scene of the massacre of a British brigade in 1842.
The road southwards to Ghazni and Kandahar was always naturally excellent and has probably needed little engineering, but the general principle of road-making in support of a military advance has always been consistently maintained, and the expeditions of Kabul troops to Kafiristan have been supported by a very well graded and substantially constructed road up the Kunar valley from Jalalabad to Asmar, and onwards to the Bashgol valley of Kafiristan.
Eastward it extends to the border of Jalalabad at Jagdalak; southward it includes the Logar district, and extends to the border of Ghazni; north-westward it includes the Paghman hills, and the valley of the upper Kabul river, and so to the Koh-i-Baba.
Within the limits of this boundary Afghanistan comprises four main provinces, Northern Afghanistan or Kabul, Southern Afghanistan or Kandahar, Herat and Afghan Turkes Ghilzai and Hazara Highlands, Ghazni, Jalalabad and Kafiristan.
Between Jalalabad and Peshawar is the Khyber pass.
The climate of Jalalabad is similar to that of Peshawar.