Tanzanian nationals require an entry clearance. Applications are submitted to the commercial partner in Dar Es Salaam and then sent to the hub in Pretoria for processing.
Following a change to the rules in April 2015, there is no special category for spouses who apply for the Standard Visitor Visa. All applicants should include bank statements, employment contract, and salary slips where available.
The controlling reference for what other documents can be submitted is Visitor: supporting documents guide. Another document to get famailiar with is Visit Guideance which explains how the rules are applied towards reaching a decision on a given application.
See Should I submit bank statements when applying for a UK Visa? What do they say about me? for a discussion about what they infer from a series of bank statements.
Beyond these, your wife should submit supporting evidence for every claim she makes. This is where a lot of people go wrong and it's worth studying the application carefully to substantiate each and every claim. Submitted evidence needs to be in sync with the applicant's claims and applicants who simply bombard them with lots of stuff are inviting problems.
For example, she claims to be married, so this would call for a marriage certificate (or an appropriate substitute). Also, she claims to have accommodation at a flat you have rented, so this would call for your tenancy agreement and something showing the flat had capacity for two people and something from the landlord showing they agree to having visitors staying in the flat.
Employment references, on the other hand, are not generally relevant because visitors are not required to prove they are punctual and diligent and exhibit attention to detail and so on. It's bombarding them. Worse, it can backfire if they think your wife will be seeking employment in the UK.
We cannot go through all of the cases because it would make your question too broad and covering everything is a solicitor's job in the first instance.
So in summary, read the guidance on UKVI's site along with the canonical answers on this site. Remember that you can always instruct a solicitor who can examine your wife's circumstances and prescribe exactly what documents are needed.