What are the achievements of pre-historic peoples?
I'm not sure exactly what the question refers to so I'm speculating a bit.
Pre-history is traditionally defined as that part in history happening before we had any written records of it. Some civilisations (Sumerians, Egyptians) developed writing very early, while others (Incas, Kingdom of Benin) developed technologically and socially without it. It would be technically true that pre-history ended around 3200 BCE in Egypt and around 1900 CE in New Guinea, but what do we mean/imply when we say it?
The concept of pre-history is more useful for giving you an idea of how much we can know about a culture rather than how advanced they actually were: for instance, say you want to study wars between Romans and Celts: Romans left historical records, the Celts did not; whose side of history are you going to get? There is a bias that needs acknowledging. (Also, the term 'pre-history' was coined in the 1830's by French anthropologist Paul Tournal, in a very euro-centric cultural environment).
Writing was invented by Mesopotamians somewhere between 6th and 4th millenia BC (evolving out of a counting system invented around 8000 BC). Mesopotamian writing dates from about 3600 BC, Proto-Elamite scripts from 3200 – 2900 BC, Egyptian hyeroglyphs from about 3200 BC ; the Chinese, Indus, Cretan and possibly Olmec scripts developed in 3rd and 2nd millenia BC; with the alphabet being invented by Phoenicians in 19th Century BC, then adopted in a modified form by Greeks and Etruscans.
Now, if you look at overall human developement, historians agree that the Stone Age, nearly contemporaneous with the evolution of human beings as we know them, started about 3 millon years ago and ended between 4500 BC and 2000 BC; which pretty much coincides with the apparition of writing. Now, I assume your question refers to what had the human species achieved in terms of civilisation until Sumerians invented writing, so let's see:
Paleolithic (early Stone Age) covers roughly 99% of human prehistory, until about 10000 BC. People lived on hunting and gathering, manufacturing stone, bone and wood tools; they organised in egalitarian nomadic bands (20-100 people). They made use of furs and vegetal fibres for clothing and shelter purposes. The first forms of religion (animism, totemism, fertility cults, idol-worshipping) and the first forms of art (cave painting, decorative objects, jewelery) developed in middle paleolithic (from 300,000 to 30,000 years ago); bands and families began caring for their helpless elders. It is in upper paleolithic (50,000 to 10,000 years ago) that scholars speculate division of labour by gender first appeared.
Mesolithic (10,000 to 5,000 BC, roughly) means the apparition of pottery and the beginning of agriculture, along with more sophisticated tools. Neolithic (until 4,500-2,000 BC) is when people started settling down, building mudbrick houses, growing edible plants and domesticating animals. By the time Sumerians invented writing, some civilisations were using milk, wool and weaved linen or ploughed land with oxen. People organised in tribes and family lineages,led by a chieftain or otherwise socially stratified; private property and warfare appeared. The first metal tools appear, leading towards the Bronze Age.
It is at this stage of developement that the first civilisations started to develop writing. However, you need to remember that not all civilisations automatically started writing when attaining a certain develpment level.