The Báb proceeded to Tabriz accompanied by two of His followers

The Báb was accordingly ordered to proceed to Tabríz.  The same escort, under the command of Muḥammad Big, attended Him on His journey to the northwestern province of Ádhirbayján. He was allowed to select one companion and one attendant from among His followers to be with Him during His sojourn in that province. He selected Siyyid Husayn-i-Yazdí and Siyyid Hasan, his brother. He refused to expend on Himself the funds provided by the government for the expense of that journey. All the allowances that were given by the State He bestowed upon the poor and needy, and devoted to His own private needs the money which He, as a merchant, had earned in Búshihr and Shíráz. As orders had been given to avoid entering the towns in the course of the journey to Tabríz, a number of the believers of Qazvín, informed of the approach of their beloved Leader, set out for the village of Síyáh-Dihán and were there able to meet Him. 

- Nabil  (‘The Dawn-Breakers, chapter 12)

Reasons that prompted Hájí Mírzá Aqásí not to allow the Báb to go to Tihran

According to Mírzá Abu’l-Fadl, Hájí Mírzá Aqásí sought, by his reference to the rebellion of Muhammad Hasan Khán, the Salar, in Khurásán, and the revolt of Áqá Khán-i-Isma’ílí, in Kirmán, to induce the sovereign to abandon the project of summoning the Báb to the capital, and to send Him instead to the remote province of Ádhirbayján.

Fearing that the presence of the Báb in Tihrán would occasion new disturbances (there were plenty of them due to his whims and his poor administration), he altered his plans and the escort, charged to take the Báb from Isfáhán to Tihrán, received, when about thirty kilometers from the city, the order to take the prisoner directly to Máh-Kú. This town, in the mind of the prime minister, would offer nothing to the impostor because its inhabitants, out of gratitude for the favors and protection they had received from him, would take steps to suppress any disturbances which might break out.” (Journal Asiatique, 1866, tome 7, p. 356.)

(Footnotes to chapter 12 of The Dawn-Breakers provided by Shoghi Effendi)

Additional historical information about Hájí Mírzá Aqásí by European diplomats in Persia

Gobineau writes regarding his fall: “Hájí Mírzá Aqásí, robbed of the power which he had constantly ridiculed, had retired to Karbilá and he spent his remaining days playing tricks on the Mullás and scoffing even at the holy martyrs.” (“Les Religions et les Philosophies dans l’Asie Centrale,” p. 160.) 

“This shrewd man had gained such power over the late Sháh that one could truly say that the minister was the real sovereign; he could not therefore survive the loss of his good fortune. At the death of Muhammad Sháh, he had disappeared and had gone to Karbilá where, under the protection of the sainted Imám, even a state criminal could find an inviolable asylum. He was soon overcome by gnawing grief which, more than his remorse; shortened his life.” (Journal Asiatique, 1866, tome 7, pp. 367–36; Footnotes to chapter 12 of The Dawn-Breakers provided by Shoghi Effendi)

“Hájí Mírzá Aqásí, the half crazy old Prime Minister, had the whole administration in his hands, and obtained complete control over the Sháh. The misgovernment of the country grew worse and worse, while the people starved, and cursed the Qájár dynasty.... The condition of the province was deplorable and every man with any pretension to talent or patriotism was driven into exile by the old haji, who was sedulously collecting wealth for himself at Tihrán, at the expense of the wretched country. The governorships of provinces were sold to the highest bidders, who oppressed the people in a fearful manner.” (C. R. Markham’s “A General Sketch of the History of Persia,” pp. 486–7; Footnotes to chapter 12 of The Dawn-Breakers provided by Shoghi Effendi)

“The state of Persia, however, was not satisfactory; for Hájí Mírzá Aqásí, who had been its virtual ruler for thirteen years, ‘was utterly ignorant of statesmanship or of military science, yet too vain to receive instruction and too jealous to admit of a coadjutor; brutal in his language; insolent in his demeanour; indolent in his habits; he brought the exchequer to the verge of bankruptcy and the country to the brink of revolution. The pay of the army was generally from three to five years in arrears. ‘The cavalry of the tribes was a almost annihilated.’ Such—to adopt the weighty words of Rawlinson—was the condition of Persia in the middle of the nineteenth century.” (P. M. Sykes’ “A History of Persia,” vol. 2, pp. 439–40; Footnotes to chapter 12 of The Dawn-Breakers provided by Shoghi Effendi)

The fall of Hájí Mírzá Aqásí “two years after he had issued his decree condemning the Báb to a cruel incarceration in the inhospitable mountains of Ádhirbayján”

The numerous properties which he forcibly seized from the humble and law-abiding subjects of the Sháh, the costly furnitures with which he embellished them, the vast expenditures of labour and treasure which he ordered for their improvement—all were irretrievably lost two years after he had issued his decree condemning the Báb to a cruel incarceration in the inhospitable mountains of Ádhirbayján. All his possessions were confiscated by the State. He himself was disgraced by his sovereign, was ignominiously expelled from Tihrán, and fell a prey to disease and poverty. Bereft of hope and sunk in misery, he languished in Karbilá until the hour of his death.  

- Nabil  (‘The Dawn-Breakers, chapter 12)