The Neolithic period lasted in northern Europe for approximately 3,000 years (c. 4500 BC–1700 BC). It is characterised by the so-called Neolithic Revolution, a transitional period that included the adoption of agriculture, the development of tools and pottery (Cardium pottery, LBK), and the growth of larger, more complex settlements. There was an expansion of peoples from southwest Asia into Europe; this diffusion across Europe, from the Aegean to Britain, took about 2,500 years (6500 BC–4000 BC). Some archaeologists believe that this expansion, marking the eclipse of Mesolithic culture, coincided with the introduction of Indo-European speakers, whereas linguists prefer to see Indo-European languages introduced during the succeeding Bronze Age. Within the framework of this latter theory (the Kurgan hypothesis), which remains the most commonly accepted model of Indo-European expansion, Neolithic peoples in Europe are called "Pre-Indo-Europeans" or "Old Europe".