Amanullah Khan reigned in Afghanistan from 1919, achieving full independence from the British Empire shortly afterwards.
Before final peace negotiations were concluded in 1921, Afghanistan had already begun to establish its own foreign policy, including diplomatic relations with the new government in the Soviet Union in 1919. During the 1920s, Afghanistan established diplomatic relations with most major countries.
The second round of Anglo-Afghan negotiations for final peace were inconclusive. Both sides were prepared to agree on Afghan independence in foreign affairs, as provided for in the previous agreement. The two nations disagreed, however, on the issue that had plagued Anglo-Afghan relations for decades and would continue to cause friction for many more--authority over Pashtun tribes on both sides of the Durand Line. The British refused to concede Afghan control over the tribes on the British side of the line while the Afghans insisted on it. The Afghans regarded the 1921 agreement as only an informal one.
The rivalry of the great powers in the region might have remained subdued had it not been for the dramatic change in government in Moscow brought about by the Bolshevik Revolution of 1917. In their efforts to placate Muslims within their borders, the new Soviet leaders were eager to establish cordial relations with neighboring Muslim states. In the case of Afghanistan, the Soviets could achieve a dual purpose: by strengthening relations with the leadership in Kabul, they could also threaten Britain, which was one of the Western states supporting counterrevolution in the Soviet Union. In his attempts to unclench British control of Afghan foreign policy, Amanullah sent an emissary to Moscow in 1919; Lenin received the envoy warmly and responded by sending a Soviet representative to Kabul to offer aid to Amanullah's government.
Throughout Amanullah's reign, Soviet-Afghan relations fluctuated according Afghanistan's value to the Soviet leadership at a given time; Afghanistan was either viewed as a tool for dealing with Soviet Muslim minorities or for threatening the British. Whereas the Soviets sought Amanullah's assistance in suppressing anti-Bolshevik elements in Central Asia in return for help against the British, the Afghans were more interested in regaining lands across the Amu Darya lost to Russia in the nineteenth century. Afghan attempts to regain the oases of Merv and Panjdeh were easily subdued by the Soviet Red Army.
In May 1921, the Afghans and the Soviets signed a Treaty of Friendship, Afghanistan's first international agreement since gaining full independence in 1919. The Soviets provided Amanullah with aid in the form of cash, technology, and military equipment. Despite this, Amanullah grew increasingly disillusioned with the Soviets, especially as he witnessed the widening oppression of his fellow Muslims across the border.
Anglo-Afghan relations soured over British fear of an Afghan-Soviet friendship, especially with the introduction of a few Soviet planes into Afghanistan. British unease increased when Amanullah maintained contacts with Indian nationalists and gave them asylum in Kabul, and also when he sought to stir up unrest among the Pashtun tribes across the border. The British responded by refusing to address Amanullah as "Your Majesty," and imposing restrictions on the transit of goods through India.
Amanullah's domestic reforms were no less dramatic than his foreign policy initiatives, but those reforms could not match his achievement of complete, lasting independence. Mahmoud Beg Tarzi, Amanullah's father-in-law, encouraged the monarch's interest in social and political reform but urged that it be gradually built upon the basis of a strong army and central government, as had occurred in Turkey under Kemal Atatürk. Amanullah, however, was unwilling to put off implementing his changes.
Amanullah's reforms touched on many areas of Afghan life. In 1921 he established an air force, albeit with only a few Soviet planes and pilots; Afghan personnel later received training in France, Italy, and Turkey. Although he came to power with army support, Amanullah alienated many army personnel by reducing both their pay and size of the forces and by altering recruiting patterns to prevent tribal leaders from controlling who joined the service. Amanullah's Turkish advisers suggested the king retire the older officers, men who were set in their ways and might resist the formation of a more professional army. Amanullah's minister of war, General Muhammad Nadir Khan, a member of the Musahiban branch of the royal family, opposed these changes, preferring instead to recognize tribal sensitivities. The king rejected Nadir Khan's advice and an anti-Turkish faction took root in the army; in 1924 Nadir Khan left the government to become ambassador to France.
If fully enacted, Amanullah's reforms would have totally transformed Afghanistan. Most of his proposals, however, died with his abdication. His transforming social and educational reforms included: adopting the solar calendar, requiring Western dress in parts of Kabul and elsewhere, discouraging the veiling and seclusion of women, abolishing slavery and forced labor, introducing secular education (for girls as well as boys); adult education classes and educating nomads. His economic reforms included restructuring, reorganizing, and rationalizing the entire tax structure, antismuggling and anticorruption campaigns, a livestock census for taxation purposes, the first budget (in 1922), implementing the metric system (which did not take hold), establishing the Bank-i-Melli (National Bank) in 1928, and introducing the afghani as the new unit of currency in 1923.
The political and judicial reforms Amanuallah proposed were equally radical for the time and included the creation of Afghanistan's first constitution (in 1923), the guarantee of civil rights (first by decree and later constitutionally), national registration and identity cards for the citizenry, the establishment of a legislative assembly, a court system to enforce new secular penal, civil, and commercial codes, prohibition of blood money, and abolition of subsidies and privileges for tribal chiefs and the royal family.
Although sharia (Islamic law) was to be the residual source of law, it regained prominence after the Khost rebellion of 1923-24. Religious leaders, who had gained influence under Habibullah Khan, were unhappy with Amanullah's extensive religious reforms.
Conventional wisdom holds that the tribal revolt that overthrew Amanullah grew out of opposition to his reform program, although those people most affected by his reforms were urban dwellers not universally opposed to his policies, rather than the tribes. Nevertheless, the king had managed to alienate religious leaders and army members.
The unraveling began, however, when Shinwari Pashtun tribesmen revolted in Jalalabad in November 1928. When tribal forces advanced on the capital, many of the king's troops deserted. Amanullah faced another threat as well: in addition to the Pashtun tribes, forces led by a Tajik tribesman were moving toward Kabul from the north. In January 1929, Amanullah abdicated the throne to his oldest brother, Inayatullah, who ruled for only three days before escaping into exile in India. Amanullah's efforts to recover power by leading a small, ill-equipped force toward Kabul failed. The deposed king crossed the border into India and went into exile in Italy. He died in Zürich in 1960.

  Tajik Rule, January-October 1929 
The man who seized Kabul from Amanullah Khan is usually described by historians as a Tajik bandit. A native of Kala Khan, a village thirty kilometers north of Kabul, the new Afghan ruler dubbed himself Habibullah Khan, but others called him Bacha-i Saqqao (Son of the Water Carrier). His attack on Kabul was shrewdly timed to follow the Shinwari rebellion and the defection of much of the army. Habibullah was probably the first Tajik to rule this region since before Alexander the Great arrived (although some historians believe the Ghorids of the twelfth century to have been Tajiks).
Little is written of Habibullah Khan's nine-month reign, but most historians agree that he could not have held onto power for very long under any conditions. The powerful Pashtun tribes, including the Ghilzai, who had initially supported him against Amanullah, chafed under rule by a non-Pashtun. When Amanullah's last feeble attempt to regain his throne failed, those next in line were the Musahiban brothers, who were also Muhammadzai Barakzai and whose great-grandfather was an older brother of Dost Mohammad.
The five prominent Musahiban brothers included Nadir Khan, the eldest, who had been Amanullah's former minister of war. They were permitted to cross through the North-West Frontier Province to enter Afghanistan and take up arms. Once on the other side, however, they were not allowed back and forth across the border to use British territory as a sanctuary, nor were they allowed to gather together a tribal army on the British side of the Durand Line. However, the Musahiban brothers and the tribes successfully ignored these restrictions.
After several unsuccessful attempts, Nadir and his brothers finally raised a sufficiently large force--mostly from the British side of the Durand Line--to take Kabul on October 10, 1929. Six days later, Nadir Khan, the eldest of the Musahiban brothers, was proclaimed King Nadir Shah. Habibullah fled Kabul, was captured in Kohistan, and executed on November 3, 1929.

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