The emergence of borders
Nowadays, borders are clear limits between two countries. Sometimes with tolls and controls, other times with guards or armed militaries to prevent people to go in or out. They can be closed or wide open. They can be crossed. They are also fluctuating. They have been here all our lives. The questions we can ask ourselves is the followings: when and how did they appeared?
The first limits are the ones of the Empire
The first evidence of borders we have come from the Roman Empire with limes, a physical wall. Those delimitations were not only to mark their territory but were also a strategic place. They were used as starting points for upcoming assaults on their opponents. Military camps were installed with crop fields for the soldiers to sustain.
However there is a major difference with our borders. They were defined by the Empire desire solely and does not result in an agreement with surrounding countries.
A world without borders
The concept of borders implemented by the Romans disappeared at the same time as the Empire itself for hundreds of years.
During feudality, in Europe, there were no borders, no demarcation between Lords. This comes from the fact that power applies upon people and not lands. The fidelity is from vassals to their leader regardless the territories. Indeed, this factor varies a lot due to conquests so no stable devotion can be put upon lands.
Maps, States and borders
This point of view is called into question with the rise of monarchs during the end of the Middle Ages. They started to create administrations and the premisses of entities which will become States. This will be concretised in 1648 with the Westphalie Treaty  organising Europe as an ensemble of States with borders driven by peace. Those borders will become stronger with cartography and clear limits of each State drawn on maps.
However, even if the people starts to identify itself as part of a unit determined by land and not just rulers, we have to wait until François 1er to get the first clue of a national and territorial identity when he imposes the French language in his kingdom.
This identity will bloom with the French Revolution, when the citizens will appropriate to themselves the borders along with patriotic values. It will lead to a declaration: France will remain in its borders as acknowledges by neighbour States.
A moving line
Even though the borders were born with the idea of peace in mind, they evolve according to conquest, war and negotiations of monarchs. They do not reflect limits between different cultures or languages.
From the empires in Europe, nationalities will emerge thanks to revolutionary events, like in France. We have the example of Italy and Hungary then ruled by Austria, Germany who build itself around Prussia.
Then there is the case of African States whose borders were drawn in 1885 during the Berlin Conference . Here, the border is not just geopolitical as intended with the Westphalie Treaty. Indeed, it leaded to massive legal or illegal exchanges between countries, sometimes right across borders. It resulted in the adjustments made by borderers to adapt this new social and economic situation.
Specific behaviour of borderers is not exclusive to African countries. There is no denial that living so close to a border, to another country, to another culture, result in changes and adaptations for people.
The Finnish-Russian border, for example, has been studied with the situation in Värtsilä (Finland) . In this border city, the institutional practices occurs at various spatial scales with no absolute distinction between global and local operations from one side or the other of the border.
Another exemple, the case of Germany, and more specifically Berlin, will be explore with more details in a further post.
From defined lines to blurry delimitations
However, the concept of border is changing over the past two decades. Several factors are taken into consideration to consolidate this theory .
First, the border removal in Schengen Area in Europe allowing European citizens to move freely to other countries. This is accompanied with easier access to travelling possibilities with cheaper aerial companies, also improving people mobility.
Then, we have a rift more important than ever between rich and developing countries. New cultural or linguistic differences emerge.
Finally, the internet repeals common borders by giving individuals access to the whole world from a single computer or a smartphone, unifying people no matter where they are on Earth.
Borders were made to separate us, to protect us. It helped us build belonging to a nation. But it is slowly changing and are not that obvious anymore. One thing for sure, the borders of today are not the borders of tomorrow.
 Westphalie Treaty. http://www.pax-westphalica.de/ipmipo/indexen.html
 De Bli, Harm J. “Geography: Realms, Regions, and Concepts.” Peter O. Muller, Jan Nijman, 16th Edition, Wiley, November 25, 2013. ISBN: 978-1-119-30189-9
 Paasi A. – Territories, boundaries and consciouness. The changing geographies of the finish-russian border, Chischester, Editions Wiley, 1996. ISBN: 978-0-471-96119-2
 Bromberger C., Morel A. – Limites floues, frontières vives, Paris, Editions de la Maison des Sciences de l’Homme, 2001. doi:10.4000/books.editionsmsh.2898
H. Velasco-Graciet. La frontière, discontinuités et dynamiques; Des frontières et des géographes. http://geoconfluences.ens-lyon.fr/doc/typespace/frontier/FrontScient.htm