Here are some Twitter comments:
The map is one produced by: Map of Global Terrorist Attacks produced by Centre for Strategic and International Studies, using the University of Maryland’s START database for all terrorist attacks between 2012 and 2015. It is a bit unfair because there were attacks before and after those years, but still at an unusually minimal level for Europe. Here is a larger area:
Here is one for most of the world:
Here is the source map.
Zero for Poland is not consistent over the years as in this graph from Statista:
There is no single international definition of ‘terrorist attack’. The ‘Global Terrorism Database’ defines them as intentional threats or acts of violence perpetrated by non-state actors. The ‘Global Terrorism Database’ ignores ‘state terrorism for some reason known only to itself.
Poland does not have a ‘no-migrants policy’, although, Poland does have very low foreign migration compared to other EU countries. EU citizens have the right to live and work in any other EU country, with some exceptions. As a member of the European Union, Poland’s immigration policy includes this freedom of movement. Poland has the lowest foreign-born population by percentage in the EU. Only 1.7% of people living in Poland in 2017 were born outside the country compared to, for example, 10% in Italy and 13.4% in the UK. Norway had a high foreign-born population of 15%.
In 2017, around 77,000 foreign nationals migrated to Poland. This is equivalent to 0.2% of its population. That level is low by EU standards. Contrast this to Norway in 2017 which had a foreign immigration level equivalent to about 0.9% of its population. Sweden also has a high level of foreign immigration with 18% of its population being foreign born.
The maps above show all the terrorist attacks, not just Islamist ones, so you find terror attacks committed by ethnic separatists (including Basques, Corsicans, and Irish), as well as acts of environmental and other terrorism.
Other countries on the map are also terror attack free including: Lithuania, Latvia, Slovakia, Romania, and Slovenia.
Why then does Poland have a low Terrorism count? Poland is very ethnically homogeneous. According to the 2011 census, 98.1 per cent of the population were born in Poland. There are small numbers of German and Ukrainian born citizens and a few ethnic minorities. So we can consider Poland to be almost monoethnic. This monoethnicity is a major reason for Poland’s low terrorism figures. Ethnic minorities small and peaceful with few conflicting demands. There are no separatist movements nor religious incompatibilities.
Polish Muslims have assimilated over the centuries and have been strong Polish patriots for a long time. There are around twenty to thirty thousand Tartar Muslims in Poland. However, they are indistinguishable from their neighbours. However, the 2011 census only five thousand people listed Islam as their religion. It appears that different religions operating side by side over centuries pick up characteristics from each other such that the characteristics such as ‘common decency’ and general philosophical outlook become similar. Mixing of peoples from different regions irrespective of religion or colour is the strife causer. Religion and colour just makes the differences more visible. I have heard Polish people say that the Ukrainians are our ‘brothers’. Just like Australians treat New Zealanders. The relationship is seamless
Poland is not a honey-pot for migrants. Poland is a comparatively poor country by the Europe’s standards. It has slim welfare availability and few jobs for people that do not speak the native tongue. The people of Poland are not keen to absorb migrants, and certainly have no enthusiasm to accept Muslim refugees or migrants. Around seventy-one percent of the citizens are against Muslim intake. Life under the Ottomans should not be forgotten.
Poles can observe the problems to the west and see what large scale race mixing and immigration from the ‘developing world’ has done to other countries. They choose to avoid the maelstrom. Why would Poland accept migrants and assylum seekers to prove some negative comments from provocative media? Why would damage its monoethnicity and risk its harmony to prove that it is not ‘racist’. Racist is used as a weaponized word to alter situations in European countries but not in Israel – the country with strong affiliation to the leading people in the media. Who is advocating for Israel, or Japan, or China to take Muslim refugees. Israelis talk of a second holocaust of their people from low birth rate and intermarrying with Christians. 
Most countries in the West have been turned multiethnic and multicultural. The East is much more monoethnic.
Of interest, recently, Czech Republic President Milos Zeman made a fascinating call to arms. He urged citizens to arm themselves against a possible “super-Holocaust” carried out by Muslim terrorists. Interestingly, there are less than four thousand Muslims in the Czech Republic, a country of ten million people. Gun purchases had a dramatic rise. One shop owner in East Bohemia told a local paper that people were scared of a “wave of Islamists.” The Czech interior ministry is now pushing a constitutional change that would let citizens use guns against terrorists. 
Just do not forget that terrorism in Europe has killed in excess of eleven thousand people in in more than eighteen thousand attacks since early 1970. 
 https://www.aish.com/jw/s/48899452.html Low fertility and high intermarriage are pushing American Jewry toward extinction.
 https://www.washingtonpost.com/graphics/world/a-history-of-terrorism-in-europe reporting data from the University of Maryland National Consortium for the Study of Terrorism and Responses to Terrorism’s Global Terrorism Database, which tracks more than 170,000 foreign and domestic incidents worldwide.