Possibly, there is no other kingdom in the annals of history other than the Hindu Shahis of Zabul who stopped an imperial juggernaut in it’s tracks and survived, but is thrown into the dustbin of history. The main reason for this is that the case is treated as Islamic Invasion of India and not Arab Invasion of India. There are two highways into India, one through the Thar Desert and the other through the passes of Afghanistan. Sind blocked the advance through the desert for almost sixty years before succumbing while Zabul did not fall, but was conquered by local successors of the Arab empire.
It is said that the kingdom of Zabul was setup by a brother of the then Kabul Shahi ruler. Just like anything else related to India, we don’t know what their ethnicity is, what their history is, where they came from and what happened after the fall. They were on the cross-roads of India, Persia and China, and generally had China as their suzerain. Their realm was in Ghazni-Qandahar area. They ruled from Ghazni and Zamindawar and were Sun worshippers. The Arabs called these rulers Zunbils(or Zibils)(Sanskrit Janapala?) or Rutbils(Sanskrit Prantapala?) and the kingdom as Zamindawar or al-Rukhkhaj. The word Zunbil originated from Middle-Persian original Zun-datbar, ‘Zun the Justice-giver’ and Zamindawar from Zamin-i-datbar, ‘Land of the Justice-giver’. Chinese called it Hsieu-yo-kou(country of Hsieu-yo – Zibil). The word Rutbil came from the Turkish iltäbär. Both the countries were under Chinese suzerainity till the Battle of Talas. For instance, an embassy was sent in 719 from Kabul and Zabul to China to confirm their accession. The last embassy was sent in 753. We don’t know their names but below are three of the earlier rulers of Zabul –

Rutbil(670-683) – elder brother of the Kapisa Barha Tegin, split the kingdom and started ruling from Zabul. Fell in battle against the Arabs
Shih-yü or Shiquer ??-738 he was a nephew of Khurasan Tegin Shahi of Kapisa
Ju-mo-fu-ta or Rumofuda 738-??
The first Arab invasion of Zabul happened in 661 AD and the fight continued till 865 AD when the last Zunbil fell. Though they are closely related, there were cases when Kabul occupied Zabul(710) and Zabul occupied Kabul(711 – the ruler is killed)
Below is a synopsis of the interaction between both the kingdoms.
661 AD: As a part of the attempt to punish Peroz of Persia, the field armies under the command of Abdurrahman ibn Samura raided Zabulistan with 6000 soldiers. Khwash, Bust, Khushshak, Razan, Kabul fell before them. The royal sun temple at Zamindwar is desecrated. In return for the success, Sistan was made a separate governorate with ibn Samura as governor
673 AD: Another Arab army raids Zabulistan and the Zunbil agrees to pay a tribute of 1 million dirhams
681: Yazid ibn Ziyad, brother of Salm ibn Ziyad, the governor of Sistan invades Zabulistan. The army is crushed in the Battle of Ghazni, Yazid is killed and his brother Abu Ubayda captured. The relief army sent under Taha ibn Abdillah al-Khuzhai is also a failure and they had to ransom off Abu Ubayda and other prominent Arabs for 500000 dirhams
685: The first Zunbil invades Sistan but is killed
693: Arabs invade Zabul. The army is defeated
697-98: Ubaidullah ibn Abi Bakrah invades Zabul with an army consisting of Kufans and Basrans. The Kufans are led by Shurayh ibn Hani al Harithi al-Dabibi and Basrans by Ubaidullah himself. The army advances deep into Zabul but is crushed. Ubaidullah dies of grief
699: To wipe out the shame of the last invasion, Abdurrahman ibn Muhammad ibn al-Ashath was sent with a new army of Kufans and Basrans. This army, 40000 strong, was equipped with the best possible equipement and aptly named the Peacock Army. Abdurrahman advances till Kandahar and stops there to consolidate the gains. But the Governor is not ready for that and forces them to advance. When the soldiers understand that the actual reason for the invasion is settlement in the hills, the army rebelled and advanced till Iraq where it was defeated by the Syrians. Abdurrahman flees back to Zabul and dies as a refugee there in 704.
711: Qutayba ibn Muslim advances against the Zunbil. The Zunbil submits without a fight.
738: Zabul defeats the Arabs
This is the end of Arab invasions. The time for the local rulers has come.
~850: Daud al Abbas of Balkh advances till Ghazni but retreats
865: Salih, the dispossessed Amir of Bust retreated into Zabulistan. Salih and the Zunbil fall in the battle against Yaqub al Laith, the founder of the Saffrids. End of Zabul as a kingdom, the Zunbil’s family captured
867: A cousin of the Zunbil, who is made the Saffrid governor of Zabul rebels unsuccessfully.
869: Zunbil’s son escapes and raises an army in Zabul. He was forced to flee to Kabul
870: To punish the last Zunbil’s son, Yaqub al Laith raids Kabul. Panjway, Tiginabad, Ghazna(Ghazna’s fortress is destroyed), Gardiz(ruled by Abu Mansur Aflah), Bamiyan and Balkh(ruled by Daud Al Abbas) and Kabul. The Zunbil’s son is captured in Kabul.