Punjab lies to the east of the Pashtun region and has shared borders with Afghanistan at various points in history. For several centuries, dynasties centered in modern Afghanistan expanded towards Punjab, such as the Kushans, Kidarites, Hephthalites, Ghaznavids, Ghurids, Khaljis and Durranis. Other kingdoms common to both regions include the Indo-Scythians, Indo-Parthians and Kabul Shahis. In his 1857 review of J.W. Kaye's The Afghan War, Friedrich Engels describes Afghanistan as an extensive country of Asia which formerly included... a considerable part of the Punjab. In the 19th century, the Sikh Empire originating in Punjab made a series of incursions towards the Afghan frontiers, capturing large swathes of territories to the Khyber Pass.