 The word distribution of the human population is controlled by a density of the population, the number of people per square kilometer or number of persons per square miles. So this is actually controlled by again the economies of the regions and the resources, the location of the country and the most important is the facilities or opportunities which are suitable for the human cluster. So here we are dealing with the today discuss the density of the human population. Now what is density? It is the measurement of the number of people per square kilometer. Population density persons per square kilometer in South Asia was actually 350.18 in 2013. So it is one of the highest density of the word. Why because the persons are living in per square kilometer is large. So why because of the things which are suitable for agriculture. So that's why persons are living in the rural areas. But we see that the developed word is in the urban population, we get densities like this, but the farm lands or rural areas where there is a rural population, there is less per square kilometer population. So in the developed word and developing word, we see some differences. So why because the developed economies, most of the persons are living in the urban areas. But in the developing word, most of the people are living in the rural areas. So that is actually the difference between the two economies. Now this is word map and it shows the human population density. So it is actually controlled by the areas which are under the human clusters. So we see that the areas where there are more densities are the ones that come in major clusters. Like in East Asia, you see Japan, South Korea, North Korea and China. And in South Asia, India, Pakistan, Bangladesh are under the high density zones. In Europe, again we have the example of certain countries which are under the high densities. But one thing is very important here that when we talk about any country of density, there are evenly distributed densities. Some areas are under mountains, some are under planes, some are under the water bodies, some are under the deserts. Like in Pakistan, again, the Pakistan 60% of the total area is under mountain and semi-mountain regions. But 40% are in deserts and lowlands. So same is the case with the USA where water bodies are present and mountain areas are in the western side, eastern side, there are mountains. So those are actually the areas which are under less population. So thinly populated areas will be where there are mountains or deserts. But no population in those areas, like in the water body, if there is a lake, it won't be there. So it means density is actually controlled by the suitable regions. So when we are discussing the densities of the population, human population, two things are very important here. Number one is the arithmetic population density. It is actually a density which is total area divided by the total number of population. Take the example of Egypt, which with the population of 71.1 million in 2002 has a seemingly moderate arithmetic population density of 185% per square mile. However, it is mostly in desert and the vast majority of the population is crowded into the valley and delta of the river Nile. It is estimated that 98% of the all Egyptian live on just 3% of the country's land. So the arithmetic population density figure is pretty well meaningless here. Number two is the type of the population density is the physiological population density. It is actually a population density relates the total population of a country or region to the area of cultivated land it contains. This is called the physiological density or physiological population density, defined as the number of people per unit area of agriculturally productive land. Now this is the map of the Egypt. Here we can see that the darker shade represents the densely populated area of the country and that is actually the river Nile area of the Egypt and the rest of the Egypt is covered with desert. So when we are discussing the physiological population density of any country like we have the Egypt, although millions of people live in its great cities Cairo and Alexandria and smaller urban centers, the irrigated farmland is densely populated. When the entire population is divided in Egypt's confined arable land, the resulting physiological density figure for the year 2002 is 9,245 per square mile. This number is far more reflective of Egyptian population pressure and it continues to rise rapidly despite Egyptian efforts to expand its irrigated farmland. Now Pakistan ranks number 6 in the list of the countries by population. The population density in Pakistan is 233 people per square kilometer and 37% of the total population belongs to the urban area. So again Pakistan is a densely populated area of the world but most of the regions are vacant like desert area of Pakistan. So that's why these areas are thinly populated regions of the country but most of the population belongs to the Punjab and Sindh. Why? Because of the river land and the canal irrigation system and the urban centers where we have mining. Those are very important areas like in Balochistan we take the example of Sui. So when the deposits of gas come out from there, now this area becomes one of the population cluster of Balochistan. So these are the opportunities where the sources are, where the availability of soil which is suitable for agriculture is. So this is actually an example behind the population cluster.