While the USD is indeed a major currency, the ZAR is not, and therefore, the pair that the two make is not a major pair either. The US economy is quite commodity focused, though that does not make the pair a commodity one.
The USD permeates the global economy on levels no other currency has ever managed to accomplish. Most of the global trade is conducted in US Dollars, which is by far the most traded currency in the forex market. It goes without saying that the USD is in fact the most popular reserve currency too.
Because it is such a global means of payment, it makes perfect sense that there is more USD held outside of the United States than within.
In addition to the US, the USD is the official currency of 7 other nations. A further 23 countries have their currencies pegged to the USD.
The South African Rand came into being together with the Republic of South Africa, in 1961. Upon its introduction, the ZAR was superior to the USD valuation-wise. All that seems like ancient history now, that a USD is worth more than 13 ZAR.
Even as recently as 1984, a USD was worth only 1-2 Rand.
Needless to say, since its inception, the ZAR was hit by various crises stemming from the shaky political situation in the country.
Besides South Africa proper, the ZAR is the currency of the Common Monetary Area, which includes Lesotho and Swaziland. Namibia also uses the ZAR.
From the above, it’s quite obvious that most trading opportunities on the USD/ZAR pair come from the ZAR side of the equation. Gold and diamond prices seem to have the biggest impact on the pair. South Africa is indeed a top global gold and diamond producer, though lately, the problem of mine exhaustion has reared its head.