Despite the greatest of care and the best of intentions things sometimes get misplaced.

But imagine if you misplaced Thomas Jefferson's Declaration of Independence, or that great English statement of liberty, the Magna Carta — both of which would count as a major whoops.

Dull to look at but historically significant, the draft proposal is in good condition. ( ABC News: Simon Royal )

South Australia Parliament Research Library director Dr John Weste explained he felt a little like that recently when he was sorting through a pile of uncatalogued and very undistinguished looking documents.

"One of them was the sort of thing with a very dull, plain coloured cover with a bit of crayon on the front," he said.

"If you weren't concentrating you'd throw it in the bin. I very gingerly opened it and thought, 'Oh this isn't the sort of thing that should be just sitting on a book shelf'."

And it was definitely not rubbish bin material either.

What Dr Weste found was a proposed charter for the establishment of South Australia.

The 1834 document pre-dates the British Parliament's South Australia Act, and indeed King William IV's formal letters patent, which established the colony in 1836.

"It's one of the rarest items we've got, and the equal oldest South Australian document," Dr Weste said.

Dr Weste said there were just a handful copies of the draft charter known to exist. This latest find takes the number to six.

By way of comparison, when Thomas Jefferson finished the Declaration of Independence, 200 copies were made, of which 24 are known to still exist.

A vision splendid for the River Torrens published in 1880. ( ABC News: Simon Royal )

Draft charter surprisingly brief

Despite being an historic heavyweight, the SA draft charter is not only dreary looking, it is also surprisingly brief — just a few pages long.

One of the mysteries of the parliamentary library copy is that the last few pages are joined at the top, having never been cut by the printer.

"That presents us with a real conundrum when it goes for restoration — do we cut the pages so we can read it, or do we keep it original?" Dr Weste said.

The document talks about stable government in the new colony being beyond the means of any private individual or company, describing it as the province of a "mother" government.

There is mention of the recently rebellious American colonies too. Some 60 years on from the War of Independence it was obviously still a touchy subject for the British.

Having narrowly avoided the bin, the proposed charter is now kept securely in a locked vault.

Dr John Weste shows the storage location where the documents were found. ( ABC News: Simon Royal )

Prominent South Australians look over cache

Dr Weste showed the charter to the ABC, along with former premier Lynn Arnold and Kaurna elder Lewis O'Brien.

"This is amazing, just amazing," Mr Arnold said.

"In the Australian context, this state and this colony as it was is distinctive.

"The draft [charter] that we have seen today is an attempt to recognise some of that."

For Mr O'Brien it was a moment of mixed emotions.

"I just thought, 'Wow, you've got this book from 1834. It's the original start of the state'," he said.

But it also marked the beginning of the end of the world as Indigenous Australians knew it.

"Well it's an odd sort of thing to look at for me," Mr O'Brien said.

"When you just think they can take your country away by sticking a flag in it or writing a bit in a book ...it's mixed."

A number of pamphlets printed on the topic of assimilation. ( ABC News: Simon Royal )

A century of Indigenous policy

The draft charter was not the only surprising find.

The collection of about 2,500 documents found on a storage shelf also included a rare copy of an 1880 plan to beautify Adelaide's famous Park Lands.

It discusses the right balance between native and introduced plant species — topics Adelaide still argues about 140 years later.

By far the greatest number of documents were a series of pamphlets from the 1880s through to the 1980s.

They shared a common theme: The place and plight of Indigenous people in the new society of South Australia.

Some represented government policy, while others were from groups advocating for Indigenous rights.

"Look at this one, this section here," Mr Arnold said, shaking his head in bewilderment.

"This distinction between people, it [the pamphlet] says 'these pensions may also be granted to full-bloods'. It's astonishing this discretion and power they had over other people's lives."

Mr O'Brien added some personal experience.

"You couldn't get a pension if you lived on a mission … that happened to my father-in-law."

A collection of historical pamphlets on Indigenous issues found at SA's Parliament Research Library. ( ABC News: Simon Royal )

The term 'invasion' used in 1940s

One pamphlet from the early 1940s used the term "invasion" to describe white settlement, language that is controversial today.

"It's how history goes isn't it"? Mr O' Brien said.

"You get the good and the bad and the ugly ... it goes in cycles."

"Some of what was being said [back then] was very progressive. There have always been people like that and I think you've got to admire them."

Exactly how 2,500 documents went missing in the first place is essentially a case of digital disruption.

When the library shifted from card-based index systems in the early 90s, Mr Weste said the most in-demand items were digitised first.

This cache was just forgotten, slipping between the cracks of the old paper world and the new digital one.

But there is one word librarians prefer never to use to describe such documents: lost.

"Well, nothing is ever really lost," Dr Weste said.

"It's more a matter they are just not entirely found."