Please note that Mommsen uses the AUC chronology (Ab Urbe Condita), i.e. from the founding of the City of Rome. You can use this reference table to have the B.C. dates
From: The History of Rome, by Theodor Mommsen
Translated with the sanction of the author by William Purdie Dickson
Taxation of Asia
The system of Roman financial administration, under which the indirect taxes as well as the domain-revenues were levied by means of middlemen, in itself granted to the Roman capitalist-class the most extensive advantages at the expense of those liable to taxation.
But the direct taxes consisted either, as in most provinces, of fixed sums of money payable by the communities--which of itself excluded the intervention of Roman capitalists--or, as in Sicily and Sardinia, of a ground-tenth, the levying of which for each particular community was leased in the provinces themselves, so that wealthy provincials regularly, and the tributary communities themselves very frequently, farmed the tenth of their districts and thereby kept at a distance the dangerous Roman middlemen.
Six years before, when the province of Asia had fallen to the Romans, the senate had organized it substantially according to the first system.(20) Gaius Gracchus(21) overturned this arrangement by a decree of the people, and not only burdened the province, which had hitherto been almost free from taxation, with the most extensive indirect and direct taxes, particularly the ground-tenth, but also enacted that these taxes should be exposed to auction for the province as a whole and in Rome-- a rule which practically excluded the provincials from participation, and called into existence in the body of middlemen for the -decumae-, -scriptura-, and -vectigalia- of the province of Asia an association of capitalists of colossal magnitude.
20. Cf. IV. I. Western Asia
21. That he, and not Tiberius, was the author of this law, now appears from Fronto in the letters to Verus, init. Comp. Gracchus ap. Gell. xi. 10; Cic. de. Rep. iii. 29, and Verr. iii. 6, 12; Vellei. ii. 6.
A significant indication, moreover, of the endeavour of Gracchus to make the order of capitalists independent of the senate was the enactment, that the entire or partial remission of the stipulated rent was no longer, as hitherto, to be granted by the senate at discretion, but was under definite contingencies to be accorded by law.
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Reference address : https://www.ellopos.net/elpenor/rome/4-03-revolution-gaius-gracchus.asp?pg=28